Re: 2114 chips needed?

From: Ruud Baltissen (
Date: 2001-01-09 08:14:04

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

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

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