Hallo allemaal, For one or another strange reason I don't see my email I sent yesterday evening :( As Nicolas already mentioned, I had over 700 2114s, or better its equivalent LC3514A (if I remember well). I had because I gave them to the club. I kept plm. 40 for myself but in time I can get more if needed. But if somebody needs some, let me know. Costs: P&P. > Pasi> I have designed a 8/16/24/32kB expansion using one 32kB SRAM and > Pasi> one TTL AND chip + some resistors + capacitor, but I haven't had > Pasi> time to design the board yet. Three month ago I made a simple 32 KB-expansion for someone piggy-backing a 62256 (32*8KB SRAM) on top of the BASIC-ROM. A 74LS21 (dual 4-input AND) took care of ANDing the RAM and BLK-lines (not BLK5 !). A simple block with 8 dip-switches made it possible to disable certain lines if needed. Some resistors were added to pull-up the disconnected lines. Worked fine. The guy later piggbacked a 6264 on top of the Kernal to be able to use these 8KB in the $A000-$BFFF area. As my construction only needed 6 switches, he could use the last two for selecting and disabling the R/W-function. Knowing that there is interest, I'll make a SCH in GIF and check it with Pasi to see if this is what he had in mind. We'll then ask Marko to put it on FUNET. > Does it differ from > > http://ftp.funet.fi/pub/cbm/documents/projects/memory/vic20/32kB.html To be honest, I haven't looked at this SCH until now. I studied it several times and my first and second thoughts were:"How can this work?" Pin 5, input 8, is connected to the R/W of the VIC thru switch 1. A (L) on this line outputs (L H H H) on the (D C B A) outputs of the 174. As input 8 has priority on all the lower inputs, the others don't care. Output C, which is connected to the chipselect of the RAM, is (H). So how can data be writen to it?. Would anybody be so kind to have a look as well? > Pasi> Using 2kB SRAMs doesn't sound very cost-effective. > > That's 0.5 kB, and nope, it ain't :) You can't beat it at simplicity > though -- piggy-back the chips and solder the 6 /CS wires. I expanded my first VIC-20 in this way using the 2114's of a brooken one (1987). The expansion worked fine but the VIC didn't work well, it didn't show colours. I didn't find out until 1998 by accident that my first VIC-20 was a NTSC-machine.:/ Groetjes, Ruud - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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