Re: Cinematronics BPROM alternatives

I finished building my little bprom replacement boards for the Cinematronics
CCPU.
See here: http://www.biltronix.com/CCPU_Custom_Chip_Replacements.html
Pictures now shown. I have lots of the PCBs so you can consider these
available.

These small boards can replace bproms from other games as well. Bascially
anything in a DIP-16.

William Boucher

----- Original Message -----
From: "William Boucher" <boucher@mnsi.net>
To: <vectorlist@vectorlist.org>
Sent: Thursday, October 01, 2009 11:56 PM
Subject: VECTOR: Cinematronics BPROM alternatives

>I dunno about anyone else, but I'm rather sick of problems related to
>sourcing and programming the old bipolar PROM chips on game boards. Tons
>of games use BPROMs but they can be very hard to source, they can be
>expensive, and finding an old programmer box that supports them is even
>tougher. I used to have an older programmer that could handle 82Sxxx parts
>but that's it. I tried burning 6301, 74Sxxx, and such equivalents but they
>failed. My present programmer, a Xeltek SuperPro/Z cost me only $100 and
>it can program all sorts of EPROMs, flash SPLD, flash EEPROM, PAL, GAL, and
>stuff like that.
>
> I repair several Cine CCPU boards each year for people and the dam BPROMs
> are always what I fear the most will have to be replaced. Since there are
> five 74S288 (32 x 8) type BPROMs on the CCPU, I decided to start with
> that. I chose an Atmel SPLD that is really cheap ($1.50), available from
> almost any electronics distributor, is available in a small SOIC package,
> and is supported by my programmer (and almost every programmer on the
> market today). I wrote separate programs for all five BPROMs (located at
> E8, C14, D14, E14, J14) using Atmel WinCUPL which is free. It produced
> the JEDEC (*.jed) files needed to program the chips. The new chips are
> flash or EE-SPLD. They are as fast as the original BPROMs. I made a chip
> adapter socket today and tried the new chip in all five locations on a
> known good CCPU board and they all worked fine. I have designed a tiny
> new PCB that will convert the new chip pin-order to plug directly into the
> CCPU original locations.
>
> I have also designed a replacement for the larger BPROM (74S287 256 x 4)
> located at F14. For a first effort, it is based on a Xilinx XC9536. I
> couldn't get all of the data to fit into a cheaper SPLD but I'm open to
> suggestions if someone has a smaller cheaper chip in mind for the job. I
> still have to build a socket adapter to try it. For now, the design is
> done and the code is written in VHDL but I haven't tried it in a running
> board yet.
>
> Also, I don't care much for old windowed EPROMs either. They're okay and
> they've proven their worth, and some guys out there still sell NOS parts
> at good prices but it's not like you can just buy them anywhere you want
> to anymore. For the Cine CCPU (or Vectorbeam Space War), I decided to try
> something else just for fun. I know someone will say "seen it, old news"
> but just in case someone else might find it interesting I'm going to say
> it anyway. I purchased some new readily available flash parallel EEPROM
> chips that my programmer supports. The OnSemi CAT28C16A is a 2k x 8 flash
> memory with the same pinout as a standard UV 2716 except that on the new
> chip, pin 21 is "/WE" and not "Vpp". If the CCPU had wired pin 21 as tied
> high, the new chip would just plug in and work. As it is, pin 21 is tied
> low and so that would hold the new chip in "write" mode and we don't want
> that. The solution I used tonight just to try it out was to program the
> chip, bend the pin outward just a little and plug the chip into the socket
> with pin 21 hanging out over the side. The board ran fine.
>
> The advantages of the EEPROM are:
> -more widely available than UV 2716 chips
> -cost is very low
> -no UV needed to erase it, programmer does it instantly
> -has 100 year retention
> -has no window so it can't be corrupted by external light sources
> -can be instantly reprogrammed for other games
>
> There's no 4k x 8 equivalent to the 2732 chip that I am aware of, at least
> not in current distributor stocks. If there was, you could do this same
> type of replacement for games such as Armor Attack and Solar Quest.
> However, there is a 64k x 8 device that is in a 28-pin package. The cool
> thing about it is that it can be plugged into the original socket with 4
> pins at one end hanging out and it has everything needed except power.
> One tiny wire jumper fixes it. Or, you can install 28-pin sockets into
> the original 24pin sockets and add the jumper to that. Also, there's a
> couple of extra address pins to tie down but that's super simple. You can
> even program up to 8 games into the new chips and add switches to operate
> the extra address pins to create a multi-game CCPU. That doesn't address
> the obvious control panel wiring differences or the audio issues, but
> still. You can make a general CCPU that can be used on the bench to test
> several different games at the flip of a DIP switch or two. This has been
> done before and is in fact old news but to my knowledge the chips
> suggested were older UV parts. I'm suggesting to use the newer flash
> CAT28C64 type as a superior replacement device. Designing a CPLD to
> reroute the control panel lines would also be easy but I like Zonn's more
> practical approach of redefining the input lines within the game source
> code such that all the inputs for all the games match and then you could
> build a universal control panel.
>
> Working with the SPLD and CPLD parts to replace old custom logic gets me a
> little pumped to dive in and start collecting whole sections into CPLDs.
> There's been lots of talk about possible single-chip CCPU boards emerging
> in the near future and that would be exciting. I'm very new to such
> devices so I expect that a project that big is beyond me for the moment,
> but I can see how more experienced designers can really get into this
> stuff and pull it off. I might not be able to make a single-chip clone
> board on my first try, but I bet I could get it under 15, maybe 10.
>
> My plan presently is to get a couple hundred of the little 32x8 BPROM
> converter PCB's made so if anyone is interested in them, let me know. I
> may work something out for the 256x8 some time soon after that.
>
>
> William Boucher
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Received on Sat Oct 24 15:25:05 2009