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General Category => Amstrad CPC hardware => Topic started by: gerald on 18:31, 17 October 12

Title: 464 and ram extension ....
Post by: gerald on 18:31, 17 October 12
... how can this work !!!

I wanted to do some test regarding C3 mode with my 464 and my memory 512k RAM extension. This extension works well on my 6128 and 6128+ however, it is not working on the 464.

Working, not working  :-\
Test show that everything written to the extension (in mode C4 to C7) is OK, what is wrong is that the base ram in 0x4000-0x7FFF is written as well.
Using a logic analyser, I can see that the DRAM is written as if no extension were connected, despite the RAMDIS signal being asserted. I also checked that RAMDIS was properly propagated from extension to the main board (pull down resistor and or gate).

From a schematic point of view, RAMDIS only prevent data read from DRAM to drive the Z80 databus. There is no direct connection between RAMDIS and the DRAM or the Gate Array. And only the Gate Array has connection to the DRAM RAS/CAS/WE, so only the Gate Array could inhibit the write.
My CPC having a 40007 GA (with heatsink), I also tested it with a 40010. Result are the same.

I cannot test with  a DKTronic extension as I do not own any.

So my question is : how the write to DRAM is inhibited when an extension RAM is selected ?

Title: Re: 464 and ram extension ....
Post by: arnoldemu on 18:52, 17 October 12
Quote from: gerald on 18:31, 17 October 12

I cannot test with  a DKTronic extension as I do not own any.
EDIT: Gerald which country are you in? I am happy to lend you mine if you are in UK or Europe.
Title: Re: 464 and ram extension ....
Post by: gerald on 19:08, 17 October 12
Quote from: arnoldemu on 18:52, 17 October 12
EDIT: Gerald which country are you in? I am happy to lend you mine if you are in UK or Europe.

I'm in France.

But before risking any HW accross the channel, can you run the following test on a 464 with a memory extension?
Any red message is a problem  ;D
Title: Re: 464 and ram extension ....
Post by: IanS on 19:41, 17 October 12
Quote from: gerald on 18:31, 17 October 12
So my question is : how the write to DRAM is inhibited when an extension RAM is selected ?
I really didn't want to spend time tracing the PCB.

Do you want to know about the other transistor on a dktronics ram board?

It looks like it's pulling MREQ up to +5v.
Title: Re: 464 and ram extension ....
Post by: gerald on 19:48, 17 October 12
Quote from: IanS on 19:41, 17 October 12
I really didn't want to spend time tracing the PCB.

Do you want to know about the other transistor on a dktronics ram board?

It looks like it's pulling MREQ up to +5v.

Hey, that's an information !!!! Thanks for your time.
Dirty trick, but that could do it.

So DK may be forcing A15 in C3 mode and MREQ in other access.

I may test that, but hell, I do not like forcing the Z80 bus  :o
Title: Re: 464 and ram extension ....
Post by: gerald on 19:50, 17 October 12
All these hacks on DKtronic ram extension let me think that the 464 (664?) was not really designed to have a RAM extension.

Title: Re: 464 and ram extension ....
Post by: IanS on 19:58, 17 October 12
I'll try and do some checks tomorrow. I only have a salae logic, but should tell me enough.
Title: Re: 464 and ram extension ....
Post by: TFM on 20:41, 17 October 12
Quote from: gerald on 19:50, 17 October 12
All these hacks on DKtronic ram extension let me think that the 464 (664?) was not really designed to have a RAM extension.

Indeed! Maybe it's time to leave 464/664 behind and move on to the 6128. Probably 99% of all CPC users have a 6128 keyboard today (and maybe some 464/664 in the shed or attic, just there to catch dust).
Title: Re: 464 and ram extension ....
Post by: Bryce on 20:47, 17 October 12
I still use my 464 and have 512K (2x 256K) DKTronics RAM expansions connected. But I'm starting to wonder if I should remove them. Pulling a negative output that has no inline resistor is a really bad idea and definitely not something I would recommend. I haven't checked the internal circuitry of the Z80, maybe the outputs have some sort of protection. But even then, that would have been designed for "emergencies" and not for regular use.

Bryce.
Title: Re: 464 and ram extension ....
Post by: gerald on 21:21, 17 October 12
Quote from: Bryce on 20:47, 17 October 12
I still use my 464 and have 512K (2x 256K) DKTronics RAM expansions connected. But I'm starting to wonder if I should remove them. Pulling a negative output that has no inline resistor is a really bad idea and definitely not something I would recommend. I haven't checked the internal circuitry of the Z80, maybe the outputs have some sort of protection. But even then, that would have been designed for "emergencies" and not for regular use.

Bryce.

The Z80 in CPC is a TTL chip and is likely to have totem-pole output. I do not think there is any protection except the main output transistor current sink capability. 
I did not find any indication on the max current the output can sink except a VOH max of 0.4V with a 1.4mA -> the pad could sink 1.4ma while still having a Vout less than 0.4V.
If you force the output high (at least higher than the minimum for being considered high by other chips), the transistor should sink as much as it gain (Beta) and base current allow it. Output voltage will increase as well a power dissipated in that transistor.

Now, should you not use the expansion anymore ? How many Z80 died from having a DKTronics extension attached? I don't know  :P
But it seems that even Amstrad did not prevent that trick nor attack DKtronics.

@Bryce, Ians, Kevin : can one of you post  a picture of the extension both side (scanned ?). Wiki picture are really too small for any analysis.

I would like to know if the interface uses any of the following expansion connector signals : CLK (pin 50) and READY/WAITn (pin 39)
READY/WAITn should be enough for the A15/MREQn hack.


Title: Re: 464 and ram extension ....
Post by: Bryce on 21:40, 17 October 12
If they really did it that way, then that should be ok for the CPU,  but it's still a dodgy hack, not exactly "Best Practise" :D When I get a chance I'll put a scope on it and see exactly what it's doing. As I have two of them connected, there are two sets of transistors pulling the signals high in parallel. I need to measure exactly what's happening on those lines.

Bryce.
Title: Re: 464 and ram extension ....
Post by: gerald on 21:52, 17 October 12
Dodgy hack, not exactly "Best Practise", agreed !
But allowing to have more RAM on the expansion port while not planned on original design is a clever trick.

I am just wondering the chronology of these expansions.
Did they appear before or after the 6128 ?
The RAMDIS signal seem to indicate that AMSTRAD planned the ram extension, but just forgot to protect the internal DRAM ?
Why no fix has been done on later version of 464 ?

By the way, has anyone a 664 service manual ?
Title: Re: 464 and ram extension ....
Post by: IanS on 21:54, 17 October 12
Quote from: gerald on 21:21, 17 October 12
@Bryce, Ians, Kevin : can one of you post  a picture of the extension both side (scanned ?). Wiki picture are really too small for any analysis.
I've put a few quick pics here - http://www.testbox2.co.uk/dktronic64K.zip (http://www.testbox2.co.uk/dktronic64K.zip) (~6MB)

Difficult to get good pics with the edge connectors on each side. And much of the interesting bits happens close to the connector.
Title: Re: 464 and ram extension ....
Post by: Bryce on 21:57, 17 October 12
I assume Amstrad messed up too. It's highly unlikely that they planned the computer to NOT have RAM expansions.

The 664 service manual is here: Service Manuals - CPCWiki (http://www.cpcwiki.eu/index.php/Service_Manuals)

Would you need to do exactly the same on the 464+? Surely they fixed it there, but I haven't looked (and I don't think any specific 464+ RAM expansions were ever released).

Bryce.

Edit: Oh yeah, regarding pictures: I have a few here of the top at least: Upgrading a Dk'tronics RAM Expansion - CPCWiki (http://www.cpcwiki.eu/index.php/Upgrading_a_Dk%27tronics_RAM_Expansion)
Title: Re: 464 and ram extension ....
Post by: gerald on 22:33, 17 October 12
Quote from: Bryce on 21:57, 17 October 12
The 664 service manual is here: Service Manuals - CPCWiki (http://www.cpcwiki.eu/index.php/Service_Manuals)
The 664 file is cursed (464KB  ;D ), and 7zip cannot open it (corrupted ?)

Quote from: Bryce on 21:57, 17 October 12
Would you need to do exactly the same on the 464+? Surely they fixed it there, but I haven't looked (and I don't think any specific 464+ RAM expansions were ever released).
I do not think. The DRAM protection is done by the PAL and the PAL is part of the ASIC, and ASIC is the same on all CPC+.
I do not have a 464+ to check, but reading 2nd bank should return garbage (floating bus) while on 464 you get 1st bank data.



Quote from: IanS on 21:54, 17 October 12
I've put a few quick pics here - http://www.testbox2.co.uk/dktronic64K.zip (http://www.testbox2.co.uk/dktronic64K.zip) (~6MB)

Difficult to get good pics with the edge connectors on each side. And much of the interesting bits happens close to the connector.


Thanks. As you said, the edge connector is a pain !!
Let see what I can get from this.
Title: Re: 464 and ram extension ....
Post by: Bryce on 22:51, 17 October 12
Then they did solve it on future CPCs, just not on the Classic. Maybe they were afraid of causing incompatibilities with existing expansions?

I'll upload my pdf of the 664 Service Manual, one minute...

Bryce.

Edit: Ok, it took more than a minute, it's rather large, but it's there now, same wiki page directly under the rar link.
Title: Re: 464 and ram extension ....
Post by: gerald on 08:39, 18 October 12
That pdf is better  :)
Title: Re: 464 and ram extension ....
Post by: Bryce on 08:46, 18 October 12
I'm a hoarder of 8-bit schematics :D If you're looking for any others (also non- Amstrad) then let me know and I can send you them directly.

Bryce.
Title: Re: 464 and ram extension ....
Post by: arnoldemu on 09:14, 18 October 12
Quote from: gerald on 22:33, 17 October 12

The 664 file is cursed (464KB  ;D ), and 7zip cannot open it (corrupted ?)

I do not think. The DRAM protection is done by the PAL and the PAL is part of the ASIC, and ASIC is the same on all CPC+.
I do not have a 464+ to check, but reading 2nd bank should return garbage (floating bus) while on 464 you get 1st bank data.



Thanks. As you said, the edge connector is a pain !!
Let see what I can get from this.
I can check this, but I think on 464+ it doesn't return garbage, it is like the internal PAL is disabled.
Title: Re: 464 and ram extension ....
Post by: arnoldemu on 10:04, 18 October 12
Quote from: gerald on 21:52, 17 October 12
Dodgy hack, not exactly "Best Practise", agreed !
But allowing to have more RAM on the expansion port while not planned on original design is a clever trick.

I am just wondering the chronology of these expansions.
Did they appear before or after the 6128 ?
The RAMDIS signal seem to indicate that AMSTRAD planned the ram extension, but just forgot to protect the internal DRAM ?
Why no fix has been done on later version of 464 ?

By the way, has anyone a 664 service manual ?
I'm guessing the costdown 464 is fixed, but the original 464 is not.
I have both of these 464s.
I will try and find time this weekend to re-check and to run your tests on all the cpcs I can.
Title: Re: 464 and ram extension ....
Post by: gerald on 15:30, 18 October 12
To check that the cost down is fixed, you would need a  6128 memory extension.
From picture in wiki, 6128 ram extension does not seems to have the 2 transistors that force A15/MREQn.
Title: Re: 464 and ram extension ....
Post by: gerald on 19:27, 18 October 12
Quick status

I got the 464 working properly in mode C4-C7 by driving mreqn high during access to memory extension. Base ram is no more corrupted.
Next step is to deal with C3 mode. I hope to have a full 6128 compatible behaviour by preventing the ROM to appear at 0x4000-0x7FFF range when enabled.

464 still alive  ;)
Title: Re: 464 and ram extension ....
Post by: TFM on 20:32, 18 October 12
If that kind of expanson would be doable, then a lot of my programs - not only FutureOS - would work for the CPC464 too. Good luck!
Title: Re: 464 and ram extension ....
Post by: gerald on 20:43, 18 October 12
Quote from: gerald on 19:27, 18 October 12
Next step is to deal with C3 mode. I hope to have a full 6128 compatible behaviour by preventing the ROM to appear at 0x4000-0x7FFF range when enabled.

Latest news : DKTronics C3 compatible mode is working.

I was expecting to prevent the ROM to be visible in 0x4000-0x7FFF range by asserting the ROMDIS signal. I just forgot that the gate array will not issue a ramrdn to actually read the DRAM (ie enable the DRAM buffer to Z80 bus) because is think it's a ROM access !!!
So there is no way to get the 6128 compatibility mode. :(

Now on 464 : when C3 mode is selected

   with ROM disabled :
r/w in 0x4000-0x7FFF goes to base bank 0xC000-0xFFFF
r/w in 0xC000-0xFFFF goes to extension bank 0xC000-0xFFFF

  with ROM enabled :
w in 0x4000-0x7FFF goes to base bank 0xC000-0xFFFF
w in 0xC000-0xFFFF goes to extension bank 0xC000-0xFFFF
r  in  0x4000-0x7FFF  and 0xC000-0xFFFF return upper rom content


@arnodemu
If you have time,  can you check the 4 lines after the "memory Expansion test" message of my test when run with a dktronic extension on 464 ?
You should get :

Memory Expansion test

C0 80 C0
1C E7 80 80
E7 0C E6 E6 E5 E5 E4 E4
14 00 1C 04


Title: Re: 464 and ram extension ....
Post by: TFM on 20:55, 18 October 12
Quote from: gerald on 20:43, 18 October 12
Latest news : DKTronics C3 compatible mode is working.

Can you please give FutureOS a run and check if the mouse pointer moves over the screen like expected or if it leaves a track?
Title: Re: 464 and ram extension ....
Post by: gerald on 21:09, 18 October 12
How do I get FutureOs to run on 464, the ROM version are in slot 10 to 13 and 464 only initialize 7 and below ?
Title: Re: 464 and ram extension ....
Post by: TFM on 01:24, 19 October 12
Quote from: gerald on 21:09, 18 October 12
How do I get FutureOs to run on 464, the ROM version are in slot 10 to 13 and 464 only initialize 7 and below ?

Uups, can you try to install the ROManager ROM (the version with the Booster), it should init all 32 ROMs.
Else, let me know, I will make a ROMs:2-5 Version.
Title: Re: 464 and ram extension ....
Post by: gerald on 08:04, 19 October 12
Quote from: TFM/FS on 01:24, 19 October 12

Uups, can you try to install the ROManager ROM (the version with the Booster), it should init all 32 ROMs.
Else, let me know, I will make a ROMs:2-5 Version.
Looks like the the ROManager ROM does not work on 464. It just crash after being initialized. Behaviour can be checked in WinAPE with 464rom and basic 1.0.
If you really have time to spend, you can make 2-5 rom version, but I do not expect better behaviour of FutureOS on my extension than on DKtronics one.

Title: Re: 464 and ram extension ....
Post by: arnoldemu on 09:41, 19 October 12
[quote author=gerald link=topic=7246.msg51960#msg51960 date=1350589439]
   with ROM disabled :
r/w in 0x4000-0x7FFF goes to base bank 0xC000-0xFFFF
r/w in 0xC000-0xFFFF goes to extension bank 0xC000-0xFFFF

  with ROM enabled :
w in 0x4000-0x7FFF goes to base bank 0xC000-0xFFFF
w in 0xC000-0xFFFF goes to extension bank 0xC000-0xFFFF
r  in  0x4000-0x7FFF  and 0xC000-0xFFFF return upper rom content

[/quote]
So close except for the read of 0x0c000-0x0ffff. I will test again but I am sure this is ram here, rom only readable in 0x4000-0x7ffff.
btw good job with the fix for 464.


Quote from: gerald on 20:43, 18 October 12
@arnodemu
If you have time,  can you check the 4 lines after the "memory Expansion test" message of my test when run with a dktronic extension on 464 ?
You should get :
I may have time this weekend to do that. :)
Title: Re: 464 and ram extension ....
Post by: TFM on 15:48, 19 October 12
Quote from: gerald on 08:04, 19 October 12
Looks like the the ROManager ROM does not work on 464. It just crash after being initialized. Behaviour can be checked in WinAPE with 464rom and basic 1.0.
If you really have time to spend, you can make 2-5 rom version, but I do not expect better behaviour of FutureOS on my extension than on DKtronics one.

Oh, there is one thing I forget. If you install it into ROMs 10,11,12,13 and an additional copy of ROM A in ROM 0 then it autostarts. But don't waste too much of you time. It would have been just an easy test if C3 works or not.

Title: Re: 464 and ram extension ....
Post by: MaV on 13:31, 20 October 12
I have some pics from a recently acquired and yet untested dk'tronics 256k memory. The pcb is labeled "6128 - 256k ver.2" from 1986.

The upload failed despite the size of each of the three pictures being below 400kb. A second upload failed because the forum software tells me there's pictures with the same name already on the server??!?!

Anyway, are they even needed, and if so how shall I upload them?
Title: Re: 464 and ram extension ....
Post by: Bryce on 19:33, 20 October 12
Rename them, convert them to png and try again :)

Bryce.
Title: Re: 464 and ram extension ....
Post by: Gryzor on 15:20, 31 October 12
Or resave, or zip, or...

Unfortunately, a known issue with current platform...
Title: Re: 464 and ram extension ....
Post by: MaV on 10:56, 01 November 12
I did try again with Pngs but the result was the same. Next try: a zipped file.


Ha, that works! It's three pictures: front, back, and another one of the transistor. The last one looks like a kludge on the board. It's placed very close to the connector and crammed in a position that just doesn't look like a clean design.
Title: Re: 464 and ram extension ....
Post by: arnoldemu on 11:13, 01 November 12
Quote from: MaV on 10:56, 01 November 12
I did try again with Pngs but the result was the same. Next try: a zipped file.


Ha, that works! It's three pictures: front, back, and another one of the transistor. The last one looks like a kludge on the board. It's placed very close to the connector and crammed in a position that just doesn't look like a clean design.
please test with my program, I am interested to know what happens with config c3 with this expansion.
Title: Re: 464 and ram extension ....
Post by: MaV on 11:16, 01 November 12
Quote from: arnoldemu on 11:13, 01 November 12
please test with my program, I am interested to know what happens with config c3 with this expansion.
That's on my schedule this weekend. I have to get the DDI-Floppy going first (hopefully just the belt), then I'll be able to copy the program and test it.
Title: Re: 464 and ram extension ....
Post by: TFM on 15:43, 01 November 12
Well, the PCB tells that it is for 6128, right? So there C3 should work. But is it inteded to be used at the 464/664 too?
Title: Re: 464 and ram extension ....
Post by: gerald on 17:16, 01 November 12
@MaV : thanks for the pictures

It's interresting to see that there is still a transistor on a 6128 version. Its position would suggest it drives the MREQn signal, but the way it is mounted on the board does not allow to be sure (tracks cant be seen). MREQn forcing would for sure avoid the timing issue I had on the 6128+ with my own extension.

The A15 forcing transistor seem to have it place reserved too.
Title: Re: 464 and ram extension ....
Post by: MaV on 22:41, 01 November 12
I'll try to trace the transistor lines to their next neighbours.

AFAIK, the 256k dk'tronics for the 6128 was also compatible with the 464 and 664. I read that somewhere.
Title: Re: 464 and ram extension ....
Post by: arnoldemu on 10:12, 02 November 12
Quote from: TFM/FS on 15:43, 01 November 12
Well, the PCB tells that it is for 6128, right? So there C3 should work. But is it inteded to be used at the 464/664 too?
The reason I ask about c3, is that it has an external PAL within the expansion.
So, perhaps it has the same functionality as the PAL in the 64k dk'tronics and so the c3 configuration does not have 100% functionality with this ram.
But this is something that can be answered with more tests.
of course, the on-board pal within the 6128 will function correctly when the internal ram is selected.
Title: Re: 464 and ram extension ....
Post by: MaV on 01:44, 05 November 12
So, the transistor does indeed connect to MREQ. Unfortunately I cannot determine the type of transistor since the flat side of the package is pointing down to the PCB; I've tried  to move it a bit but the connector is in the way.

More precisely:
The base goes to the 12th pin from the right on the lower row of the connector (MREQ; back picture of PCB).
The collector goes to the 12th pin from the right on the upper row of the connector (VCC; back picture of PCB).
The emitter goes to pin 8 of the 74LS11N chip (third chip from the left; front picture of PCB).

If I researched this correctly there are two pin layouts for the 74LS11, one layout tells me that pin 8 is the output of a triple and gate, the other layout says pin 8 is one of the inputs of a triple and gate. It must be the latter pin layout as the former would not make sense.
/me confused

Title: Re: 464 and ram extension ....
Post by: Bryce on 10:04, 05 November 12
Pin 8 of a 74LS11 is definitely the output of a three input ANDF gate. Where did you find an alternative pinout??

Also. If you don't know what type of transistor it is, how do you know which pins are E, C and B ?? As it's being used as a simple switch rather than to amplify, the value won't matter that much anyway, as long as it the correct type NPN or PNP you can use any general purpose transistor such as a 2N3904 (if it's NPN).

Bryce. 
Title: Re: 464 and ram extension ....
Post by: MaV on 10:31, 05 November 12
Quote from: Bryce on 10:04, 05 November 12
Pin 8 of a 74LS11 is definitely the output of a three input ANDF gate. Where did you find an alternative pinout??
http://www.alldatasheet.com/datasheet-pdf/pdf/125563/ETC1/74LS11.html

Quote
Also. If you don't know what type of transistor it is, how do you know which pins are E, C and B ?? As it's being used as a simple switch rather than to amplify, the value won't matter that much anyway, as long as it the correct type NPN or PNP you can use any general purpose transistor such as a 2N3904 (if it's NPN).
I'm assuming that the pictures like on this page is the standard layout: What is a Transistor - Electronics (http://www.reuk.co.uk/What-is-a-Transistor.htm)

And yes, the type should not matter.
Title: Re: 464 and ram extension ....
Post by: Bryce on 10:50, 05 November 12
The second pinout (B) is for the flatpack version, the standard DIP 74LS11 is pinout A - Pin 8 = output from 3way AND gate.

The pinout for the transistor you've shown is quite common, but not a standard. There are transistors with alternative pinouts, where for example the collector is in the centre. The transistor used in the CPC+ to switch the tape motor on/off (KTC1815) has an ECB Pinout, ie: Collector in the middle.

Bryce.
Title: Re: 464 and ram extension ....
Post by: MaV on 11:20, 05 November 12
Quote from: Bryce on 10:50, 05 November 12
The pinout for the transistor you've shown is quite common, but not a standard. There are transistors with alternative pinouts, where for example the collector is in the centre.
Hm, but then the knowing the transistor type would matter after all. But I can't risk breaking its legs by leveraging the transistor. :/
Title: Re: 464 and ram extension ....
Post by: Bryce on 11:54, 05 November 12
If you know what the pins are connected to, then it's easy to work out what each pin is. Lets call them 1,2 and 3 for now. What is each pin connected to?

Bryce.
Title: Re: 464 and ram extension ....
Post by: MaV on 12:33, 05 November 12
Simply substitute 1, 2, and 3 for the E/B/C of the most common transistor pin layout.

That'll be:
1 to pin 8 of the 74LS11
2 to connector MREQ
3 to connector VCC

If you'd put the transistor in from of you with the flat side on the table and the pins pointing to you: 1, 2, and 3 are counted from left to right.
Title: Re: 464 and ram extension ....
Post by: Bryce on 13:29, 05 November 12
Ok, strange, It must be a PNP transistor with BCE pinout (probably something Japanese, 2SBxxxx) .

1 = Base
2 = Collector
3 = Emitter

But that would mean that it switches /MREQ high when the output of the AND gate is low?? What are the inputs of that gate connected to?

Bryce.
Title: Re: 464 and ram extension ....
Post by: MaV on 18:56, 05 November 12
I feared that you'd ask this.
It's almost impossible to trace the three input lines for the AND, because they go directly underneath the 74LS153 and 74LS74 to the left of the 74LS11.

But if I'm not mistaken pin 11 of the 74LS11 goes (more or less, changing PCB side 2 times) straight to the RD pin of the connector.
Pin 10 seems to go to pin 17 of the PAL16L8. Very uncertain.
Pin 9 goes to pin 2 of the neighbouring 74LS153 and to pin 2 of the PAL16L8. The line is underneath the 74LS153, so I'm having a hard time making them out. Again very uncertain.
Title: Re: 464 and ram extension ....
Post by: MaV on 19:08, 05 November 12
And the transistor is a BF240, so:

1 base -> pin 8 of the 74LS11
2 emitter -> MREQ
3 collector -> VCC

(The count on the datasheet is the other way around: 1=collector, etc. but I stick to our method to avoid confusion)


(now excuse me while I rest my bleeding eyes... ;) )
Title: Re: 464 and ram extension ....
Post by: Bryce on 20:20, 05 November 12
Ah, that explains a lot, so it is an NPN, that makes much more sense and it does switch when the AND output is high. I just wasn't expecting it to be a CEB Pinout, which are even rarer than the BCE pinouts. Is it TO-92 or SOT25? (Is it really round at the back or does it just have angles at the back).

Bryce.

Edit: Ok, I just took a look at my own DK expansion. Then I remembered that I had already uploaded pictures before I upgraded it. So you can see it here without the 74LS153 installed: http://www.cpcwiki.eu/imgs/3/35/DK64_Before.jpg (http://www.cpcwiki.eu/imgs/3/35/DK64_Before.jpg)
Title: Re: 464 and ram extension ....
Post by: MaV on 13:04, 06 November 12
Quote from: Bryce on 20:20, 05 November 12
Is it TO-92 or SOT25? (Is it really round at the back or does it just have angles at the back).
The back is completely rounded, so that means it is a TO-92.

Quote
Edit: Ok, I just took a look at my own DK expansion. Then I remembered that I had already uploaded pictures before I upgraded it. So you can see it here without the 74LS153 installed: http://www.cpcwiki.eu/imgs/3/35/DK64_Before.jpg (http://www.cpcwiki.eu/imgs/3/35/DK64_Before.jpg)
Thanks, Bryce. But the layout of the 6128 256k-dk'tronics is completely different. :(
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