Hi all,
I finally found some time to do some hardware stuff and used the time to put together the first LowerROM board. As you can see in the picture below, it is approximately the same size as the MegaFlash board. It needs to be plugged between the MegaFlash and the CPC, but I provided a pass-through connector so that no further messing about with cables is required. It will of course work without a MegaFlash, but it does disable the internal ROM 7, so if you want to use BASIC 1.0 on a 6128 and still have disc commands, then you will need to have AMSDOS / ParaDOS installed and enabled on the MegaFlash. I've done all the tests and you can still program the MegaFlash through the LowerROM board and all other expansions (RAM, Speechsynth, Lightpens, etc) will also work as long as they are plugged behind the LowerROM board. It also works on both Classic and Plus CPCs.
The EPROM contains two versions of OS/BASIC, so you can use the same device to convert a 6128 to BASIC 1.0 or a 464 to BASIC 1.1. The jumper next to the EPROM is used to choose which OS/BASIC you want, the jumper beside the LEDs is to enable/disable the external OS/BASIC (ie: disable the device). The red LED lights when the board is enabled and green when disabled. I also added a reset button (beside the green LED) for those who complained that it was missing from the MegaFlash :D
I have only ordered a few prototype boards to supply those who asked for one, but I have maybe 3 or 4 extras in case someone decides they suddenly want one.
Bryce.
Sweet, ill get one just for the reset button :)
Nice that it comes with the passthru-cable as i fear what would happen if i had to make one myself :laugh:
Hi Bryce !
I do confirm I have need of one of these.
Concerning the edge card connector for non-german CPCs, we all know it is out of stock for a long time. An unique "edge card"-to-centronics adapter by person would be more reasonable, as it will not create a penury.
Hi qbert,
Eliot still has some edge connectors on offer in his CPC Parts shop, but regarding an Edge Connector to Centronics adapter, I probably still have one here somewhere, send me a PM if you are interested in having it.
Bryce.
Hi Bryce! Wonderfull !!! Amazing !!!! Great !!!!!
After an eternity of time the last frontier has been broken! Now we can patch our lower ROM finally!!! :-)))
Unfortunately your suggestion to make it writeable from the CPC just wasn't practical from a cost point of view, but I put the EPROM in a socket, so it is possible to swap EPROMs and re-program it as you wish.
Bryce.
Oh, that's absolutely fine. And since the EPROM has 64 KB, I should even be able to program it at the CPC with the Dobbertin 4003. Well, it only can do 32 KB, but I can add a wire and a switch to make it a 64 KB version (I assume). Let's see... :)
Hmm, how do you mean? If I had known that that was a useful option I would have added a jumper to do that. Does the dobbertin 4003 use the same addresses as the LowerROM but just go up to FFFF? Or how does it work?
Bryce.
Quote from: Bryce on 21:08, 05 March 12
Hmm, how do you mean? If I had known that that was a useful option I would have added a jumper to do that. Does the dobbertin 4003 use the same addresses as the LowerROM but just go up to FFFF? Or how does it work?
Bryce.
Oh, I should tell things more clear. First a link:
http://www.cpcwiki.eu/index.php/Universeller_EPROM_Programmer_4004 (http://www.cpcwiki.eu/index.php/Universeller_EPROM_Programmer_4004)
The Dobbertin 4003 is an Eprom burner, that burns Eproms up to 32 KB (27256 for example), and since 27256 and 27512 are pincompatible: I thought I can burn a 27512 like a 27256, but have the need to supply an additional bit to one pin of the Eprom burner.
Ah, ok. You could still burn a 27C512 with the 4003 by connecting pin 1 (A15) to the 5V line (with a 10K resistor) to program the upper 32K.
Bryce.
Quote from: Bryce on 21:33, 05 March 12
Ah, ok. You could still burn a 27C512 with the 4003 by connecting pin 1 (A15) to the 5V line (with a 10K resistor) to program the upper 32K.
Bryce.
Ah Thanks!!! So a connect A15 to a switch. And this switch relys A15 either to GND or to 10K Ohm resistor (resistor connects to +5 V). Right?
You can make it even simpler, by permanently connecting A15 to the 5V supply through a 10K resistor and a simple switch that connects A15 to ground without disconnecting the 10K resistor.
Bryce.
Quote from: Bryce on 21:33, 05 March 12
Ah, ok. You could still burn a 27C512 with the 4003 by connecting pin 1 (A15) to the 5V line (with a 10K resistor) to program the upper 32K.
What's the 10K resistor for? I would probably just have connected it to 5V?
Quote from: Executioner on 23:58, 05 March 12
What's the 10K resistor for? I would probably just have connected it to 5V?
If I got that right, then the resister sets the A15 constantly to 1, but as soon as the switch is connected (GND on) the signal goes from 1 to 0, because the GND is stronger then the +5 Volt running throug the resistor.
It also may have a protective means, in case + 5V directly is too strong. But Bryce will for sure be able to explain that stuff in a better way.
Mmmm, very nice. Looks great. ;D
Cheers,
Shane
TFM has explained it perfectly. The 10K pull-up resistor "holds" A15 at VCC (5V) but limits the current to avoid any damage to the EPROM and this also lowers the current that the circuit is using. When the switch is closed A15 goes to logic 0 but there is no short circuit because the 10K resistor is between 0V and 5V. This is the standard method for "biasing". This is also the method I used on the DualOS description here: http://www.cpcwiki.eu/index.php/DualOS (http://www.cpcwiki.eu/index.php/DualOS)
The resistor can be a tiny 1/4W type because it will only be drawing 0.5mA = 2.5mW (for those who like to do the theoretical stuff) :)
Bryce.
Quote from: Bryce on 09:34, 06 March 12
The resistor can be a tiny 1/4W type because it will only be drawing 0.5mA = 2.5mW (for those who like to do the theoretical stuff)
Ah, I didn't get the fact that it switched between GND and +5V. Handy if you're using a jumper instead of a dual pole switch.
Exactly, you can use a simpler switch or even a simple push button if it's a signal that only needs to to be changed for a few seconds.
Bryce.
The really cool thing about the LowerROM is that we can even use emulators to create our own ROM couples (Lower + BASIC) and test them there. As soom as they work, we just have to burn the EPROM once. And that's it :-)
Because there are so many different variations, that's not a bad idea. As well as the different BASIC versions, people are also going to want different language versions too.
Bryce.
While experimenting with the LowerROM board I just noticed a nice little side-effect that I hadn't even thought about:
On a standard 464, only ROMs 7 to 0 are scanned on start-up, so the MegaFlash only offers the 464 the first 8 ROMs, however with the LowerROM connected with BASIC 1.1 enabled, I get the first 16 ROMs as I would on a standard 6128 :) and my 464 can make much better use of the MegaFlash. This may have been obvious, but I hadn't really thought about it.
Bryce.
HEHEHE great news, i didnt thought about that too, thats a great and most useful "effect".
cheers
Tom
Well, I just think about the Booster ROM for the 464 which will provide all 32 ROMs of the MegaFlash (when using the LowerROM).
Quote from: Bryce on 14:27, 18 March 12
While experimenting with the LowerROM board I just noticed a nice little side-effect that I hadn't even thought about:
On a standard 464, only ROMs 7 to 0 are scanned on start-up, so the MegaFlash only offers the 464 the first 8 ROMs, however with the LowerROM connected with BASIC 1.1 enabled, I get the first 16 ROMs as I would on a standard 6128 :) and my 464 can make much better use of the MegaFlash. This may have been obvious, but I hadn't really thought about it.
Bryce.
Yes, I noticed this (and it can be seen in the photo's I posted of my MegaROM)...my 464 with the 6128 firmware chip installed shows the 16 ROMS...then the picture with the MC0099A motherboard only shows the 7...
Same effect as your lower ROM board...handy side effect ;)
Can't wait to get mine ;D
Cheers,
Shane
Alas, the booster ROM hangs on a 464, whatever position you load it (even at position 7 replacing AMSDOS).
I know that problem very well because I am a 464 user... maybe there's a possible software patch, my dear TFM :D ?
Quote from: TFM/FS on 18:08, 18 March 12
Well, I just think about the Booster ROM for the 464 which will provide all 32 ROMs of the MegaFlash (when using the LowerROM).
It should work on a 464 that's running 6128 Firmware/BASIC as long as it's installed in position 15 as it should be.
Bryce.
Yes Bryce, I suppose, but while I am not the happy owner of a low-ROM switch (yet) and I can see no reason why the Booster ROM would not work on a vanilla 464 except the extra initialization starting at 8 instead of 16, I'm requiring help from your software specialist : TFM !!!
Quote from: Bryce on 23:24, 19 March 12
It should work on a 464 that's running 6128 Firmware/BASIC as long as it's installed in position 15 as it should be.
Bryce.
Yes! Absolutely!
Quote from: qbert on 23:44, 19 March 12
Yes Bryce, I suppose, but while I am not the happy owner of a low-ROM switch (yet) and I can see no reason why the Booster ROM would not work on a vanilla 464 except the extra initialization starting at 8 instead of 16, I'm requiring help from your software specialist : TFM !!!
Well, the Booster+ was done by the Inicrons. I may can access it's source in two months. But you can contact them at inicron.de and ask them for a 464 version :-)
@Bryce: Got my LowerROMs - Thanks' a lot :) :) :)
Got mine as well, thanks ;)
Time to fill some frames on my 464 :P
Well, in fact, I was asking you about that 'cause everybody know you manufactured a merged version of inicron's booster and your MF-RomManager. So I supposed the ROM initialization had no secret for you. :P
Booster is hanging the 464. Can you imagine another difficulty that expanding the indexing range for initialization from 16-31 to 8-31 ?
That's mainly by curiosity, TFM. Whatever your answer is, it does not engage yourself into future activities... :laugh: .
Quote from: TFM/FS on 20:58, 20 March 12
Well, the Booster+ was done by the Inicrons. I may can access it's source in two months. But you can contact them at inicron.de and ask them for a 464 version :-)
Quote from: qbert on 22:03, 21 March 12
Well, in fact, I was asking you about that 'cause everybody know you manufactured a merged version of inicron's booster and your MF-RomManager. So I supposed the ROM initialization had no secret for you. :P
Booster is hanging the 464. Can you imagine another difficulty that expanding the indexing range for initialization from 16-31 to 8-31 ?
That's mainly by curiosity, TFM. Whatever your answer is, it does not engage yourself into future activities... :laugh: .
Well, I used the Booster+ ROM and added the ROManager using the ROM Editor of Softbrenner 1.27. I did a disassembly, but I don't have it here. So I don't know for which reasons it reacts different on a 464. Can just assume the it's connected to the addresses where it stores the extra information of ROMs 16-31.
BOOSTER.ROM won't work on a 464 because it needs to be in position 15 not position 7. With the LowerROM swapper connected and 6128 Firmware/BASIC initialised the BOOSTER should work as normal.
Bryce.
Boiled down to a nutshell: Exactly!
Tiny Review of the G540 USB Eprom programmer:
I think someone else mentioned that they had troubles burning eproms with their old hardware, and i must admit i too had gotten a bit tired of having to drag my old XP computer out every time id need to burn a eprom with my old willem board who use the parallel port that no modern pc has anymore (and the software and driver probably dont work on a modern pc either).
So i had a quick search on ebay and noticed that USB programmers (the cheap chinese ones) has dropped a lot in price so i ordered a G540 about a month ago.
The Unit:
The G540 is as easy a programmer as you can get em. No buttons to press or jumpers to set .. the only port it has is the USB one that is both used to power it and connect with the software. And just 1 light to show the power is on and the grid&lock to hold the eprom itself.
Installing:
Included was mini-cdr with the software (and pdf manual) and a nicely printed 40 page (20 pages in english) paper manual with pictures and in a fairly ok understandable english. Clicked on the usbdriver-installer and it installed itself in about 1-2 min. on my Vista 64bit. The programming software was the usual program installer and about 30 sec. Afterwards hooking up the hardware for the first time was painless as well.
The programming software:
Pretty straight forward with the usual big easy buttons in english (very similar to the Willem software actually). Even tho the programmer can be set up to do a bunch of tasks in a row it really isnt rocket science to read/write a eprom.
Example on Reading a eprom to file dump:
1. Click the "select" to choose eprom/size (aka AM27C128 or AM27C512),
2. Insert your eprom in the programmer (the software will show a picture of the right orientation in the adapter) and lock it in with the lever.
3. Click "Read" to read the data from the eprom into the program's memory.
4. Click "Save" to save the data to a file.
Writing is equally simple and "automated" (aka "select", place it, "load", "prog").
Price: £30-ish (+£17 in import tax). I had calculated the tax but not that it would take a freakishly 5 weeks to arrive. Only took the pack about 10 days to travel tho .. the rest was because the sender was a bit of a clown and didnt write the "worth" on the pack so ive spend nearly 4 weeks waiting on ye ol import tax people who wanted a copy of the invoice etc.
In the pack:
It didnt come in a nice shiny blue box but it was in a smaller "hard" box instead. The unit itself was nicely wrapped in bubblewrap. The printed manual (slightly bend to fit in there), a usb cable (1metre-ish) and a scratched but readable mini-cdr with software v5.2 (not that it really matters today as you can download everything).
All in all:
Im quite happy with it and it fully does what i expected it to do. Very plug and play too. Quite a lot of chips it support as well (that id probably never use, lol). I got mine from this fella (but remember he is a bit of a "muppet"):
G540 USB universal programmer EPROM FLASH MCU GAL PIC | eBay (http://www.ebay.co.uk/itm/G540-USB-universal-programmer-EPROM-FLASH-MCU-GAL-PIC-/330687947135?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item4cfe89a17f)
But i strongly suggest looking on ebay.co.uk first as im sure you can find a cheaper one as there is a lot of sellers for the G540. Ive noticed that there is also other and perhaps even cheaper chinese brand usb programmers up now, just so you know ;)
Ive uploaded the software (8mb)(+manual) here as the official site seem to be down:
G540.zip - 4shared.com - online file sharing and storage - download (http://www.4shared.com/zip/2S-uT2Ox/G540.html)
Old link to the Willem guide as its got the basics about eproms:
Willem Programmer - CPCWiki - The Ultimate Amstrad CPC Community & Encyclopedia! (http://www.cpcwiki.eu/index.php/Willem_Programmer)
Got my Lower ROM board today...Very nice work as always.
Thanks Bryce for once again taking the time to continue to support the mighty CPC with your great hardware.
Cheers,
Shane
Thanks, cholo, nice review, and it's quite cheap as well!