2 Mega Byte Memory expansion

[rpalmer]

good news, the PCBs arrived today.

All I need now are the chips I had order as well and then get the sockets to build the test board and start to debug/test.

rpalmer

[CraigsBar]

Can I put my name down for 2 of these by any chance?

[rpalmer]

Once I have built and tested the first board I will begin costing them and taking orders. I dont expect any issues, but I like to walk before I run... 
So for now I will post updates and progress status as time goes on. Hopefully I can get the first built quickly once the main IC's are delivered from overseas.

rpalmer

[rpalmer]

Good news, I have just received the PALs and memory SMDs so I can now soon build the first board to debug/test.

Lets hope all goes to plan.

rpalmer

[rpalmer]

Hello everyone,

I have good news and some not so good news.

The good news is i have nearly completed the first board for testing.
The not so good news is that the TL866 minpro device wont program the Atmel ATF22V10 PALs I purchased. The TL866 will program a Lattice version, just not the Atmel version.... 
The other bad news I have to wait for more stuff (namely the Card Edge connectors for the 50-way cable I was going to connect the board to. These have been order and I hope to get them real soon.

I have found a web site (http://www.bhabbott.net.nz/atfblast.html) which has developed such a programmer and I have used it as a basis to create a PCB to build the PAL programmer to get the memory expansion board finished for testing.

If anyone is also interested in building the programmer I attached the Eagle schematic and Board for those eager to give it a try. The ".brd" file is a modified version from that generated by auto-routing in that the tracks are thicker and some of the top/bottom tracks were optimised to allow for single sided PCB production with wires for the top layer instead of a series of tracks produced. I hope there are no issues with this board

Rpalmer

[Executioner]

How much are those Lyontek chips? I've seen some 5V compatible 512Kx8 SRAMs for around AU$9 (AS6C8008-55ZIN).

There are already a number of memory expansions designed for the CPC, nothing providing the full 4MB as per the Yarek internal. 4MB plus 32 upper ROMs plus lower ROM would be nice, all in one board.

[rpalmer]

Executioner,

The memory chips were from www.reichelt.de. They cost about 4 euros each (purchased 20 for 72 euros).

The reason I did not go to 4 Mbyte is that Yarek used A10 as well to get 8 I/O address (8 I/O addresses x 512K = 4 MByte) and my IDE interface uses A10 alone meaning Yareks is not compatible with my IDE interface.

I have been looking at some how making a memory expansion to include the lower 7 address lines. There are SRAM chips for larger memory expansion and again these require voltage level converters and would make that board very crowded and complex.

As for an inclusion of a ROM board, that can be included in future as the current version has room on one side for the chips (only as SMD variety). This would take the form of a NVRAM chip rather than flash as the NVRAM has a nominal retention of 10 years (as per documentation) and would possible be easier than flash updates. The 10 year retention although less than flash is acceptable, since the board only needs to be powered up for it the "reset" the 10 years retention period clock.

rpalmer

[Executioner]

At 4 euros a piece, you could easily put 6 on a board. I'm surprised you only decode A10 on the IDE interface, but what would be nice is to include an alternative method (eg. write to an 8 bit buffer) to select alternative banks of memory, or set up a mapping scheme. In theory you could select up to 256 banks of 512K or something similar (I know it wouldn't be compatible with Yarek interface). If you were going down the voltage converter route, you could create an interface that used old PC SRAM memory modules and get access to GBs for cheap.

[rpalmer]

Executioner,

I don't think any PC has SRAM, they had SDRAM which is what you might be mistaking for. The SDRAM came in EDO and non-EDO variants and I have some in my Amiga 1200 accelerator card giving me 64Mb.

As for Gbytes of RAM that is only possible via a 8255 to setup the upper address lines to the memory address space. While possible, it does adds a lot to a larger memory expansion (board organization) and I don't think that would be taken up by many as 2Mbyte is already a substantial increase from current 512K expansion like the MX RAM/ROM board, however it does present an opportunity to see how far I could go  .

Then there is the complexity of having to use DRAM memory modules (namely DDR2/3/4 RAM modules) to in the GB range, which requires a high speed interface chip to do the refreshing while capable of handling Z80 memory actions and timing. Also the memory modules themselves such as DDR2/3/4 is much wider than what EAGLE (Free version) allows for.

I can see the need for 4Mb as SymbOS/FutureOS seem to cater for such, but for now small steps before I start sprinting to the finish line.

rpalmer

[rpalmer]

well I have replyed to the 64K memory expansion issue about the 2 MB memory expansion progress.

So attached is the first prototype build (sorry about focus I am not the good a photographer and I also had just dusted my computer space and much of it fell on to the PCB.

People will see I did not solder the grey PCB connector as I may have to directly solder a cable instead with the other end being a cable version for Card Edge Connector for my classic CPC. However the picture is what the eventual expansion will look once all of the issue are "ironed" out and production begins.

I expect to get the next PCB this week so that I can build a GAL/ATF programmer for the AFT22V10 chips that are going to handle the memory mapping side of things.

Rpalmer

[Tolkin]

Very nice board
I'm very curious how it goes on!

[XeNoMoRPH]

Hi !! .. do you have plans to sell it in the future ?

[GUNHED]

Why not 4 MB, that would be nice 

[rpalmer]

                        XeNoMoRPH,I do intend to make the available these real soon, but I have yet to get all of the bits to complete even the 1st build for testing (the Card Edge Connector being the most difficult to get as i have none to connect to my classic cpc).
I could do a "quick and dirty" adapter board to get further along, but I prefer to have all of the bits available to make a clean test without introducing other unknowns to complicate things. However, that being said I might have to make the adapter board for the first first to iron out any issues with the first build while the remaining items are waiting for delivery.

Rpalmer

[simondo]

                        XeNoMoRPH,I do intend to make the available these real soon, but I have yet to get all of the bits to complete even the 1st build for testing (the Card Edge Connector being the most difficult to get as i have none to connect to my classic cpc).

I'm really looking forward to you completing this.

I ordered these edge connectors recently for a project: http://www.ebay.co.uk/itm/5pc-Industrial-Card-Edge-Slot-Socket-Connector-25x2P-50P-2-54mm-0-1-3A-240-50-/140888533934?hash=item20cd9c6bae:m:mfmCIEHuZTPOfxiRH9vooiw#shpCntId
They ship to Oz.
The only problem is that the PCB pins are short and if you needed to solder a male edge connector to it through a PCB it will be difficult. There is a right angle version but one row of pins is still too short. I guess that's not a problem for your project though.
 
I am having issues obtaining a male PCB edge connector for my project..

[Bryce]

I am having issues obtaining a male PCB edge connector for my project..

Male edge is part of the PCB, you just lay it out and order some PCBs with your main PCB order.

Bryce.

[rpalmer]

I have created an adapter board to build which will allow me to connect the memory expansion to cpc without the need for the cable version of the card edge connector.
The adapter board is just a standard solder version of the connector and a pin header. The pin header allows for IDC cables to be made as they are more readily available now.

[attach=2]

rpalmer

[rpalmer]

I have now just about completed a built of a ATF22V10 programmer that can program GALs (or Atmel ATF equivalents). All I need now is a heat sink, I cant believe how hard they are to come by. The shop I normally go to only has the very bulky one which are way to big to put on the regulators.
I might have to build one using some scrap metal somehow.

rpalmer

[Bryce]

I have now just about completed a built of a ATF22V10 programmer that can program GALs (or Atmel ATF equivalents). All I need now is a heat sink, I cant believe how hard they are to come by. The shop I normally go to only has the very bulky one which are way to big to put on the regulators.
I might have to build one using some scrap metal somehow.

rpalmer

I doubt either of those would get hot enough to need a heatsink. Have you tried running it like that? And the holes in the PCB suggest that it was designed to just have them lying flat without a heatsink.

Bryce.

[||C|-|E||]

Even inthe worst case,a simple screw with a nut and several layers of aluminium foil would make a simple but good enough heatsink 

[rpalmer]

bryce,

The original board suggested it for the regulators since they assumed a 15V input. I have found one that is 12V, but the 5V regulator may get hot if connected for some time.
I suspect it could get by for a short time, but i rather follow the same build as what was stated and see where i go from there.

rpalmer

[Bryce]

The heat will mainly depend on the current the PCB is pulling. I can't imagine that the circuit needs very much current though.

Bryce.

[Rennert]

Í would like to buy one board

Gesendet von meinem Passport mit Tapatalk

[CraigsBar]

OK I have been away for a while, How is the testing process going?? I think I might be selling some kit as soon as I can buy 2 of these. 

[rpalmer]

Hi craigsbar,

The past two weeks have not kind to me as i had to attend to a funeral and so had my attention elsewhere.

I also have not done any testing of the expansion in that time as I have been getting my classic CPC up and running with a 3.5 inch floppy. This was something that was easier to do given the events of the past 2 weeks.

I have etched a PCB to convert the internal floppy connection to that for the PC floppy interface.
The PCB has a series of jumpers which can control side selection and ready lines and also converts the power supply to proper alignment for PC floppy use.

While many have simply "cut" cables and re-connected them to match the PC floppy interface, the PCB I created makes it easier to just simply connect cables and set jumpers.

I will put more information into the process in another thread for others to have the opportunity to do this themselves if they feel less confident in cable cutting.

On the memory expansion  I have found that the PAL programmer has a voltage regulator the wrong way around (my fault I should have known better on that one) and I also found heat sinks which will complete the build.

As for any orders, the original PCBs did not have un-used gates tied to ground and these will be hard-wired in the prototype and if all goes to plan I will get another set of PCBs with any corrections made to ensure all of the builds work as expected.

rpalmer