Arcade game repair - Page 1
Forum section: electronics / general

author: payty
author_rank: Contributor
timestamp: July 10, 2023, 05:58:35 pm
content: Hi,I am trying to repair an old Midway Arcade game (Revolution X). The mainboard contains a ispLSI 1032 device which seems to control much of the board memory (pixel RAM, ROM, palette RAM) and other areas.This chip seems to be dead as some of the outputs that control various RAM/ROM chips are floating.I have experience only with Arduino boards so this area of PAL/GAL is new to me.How can I copy the firmware inside this? Do I need a special programmer?

author: james_s
author_rank: Super Contributor
timestamp: July 10, 2023, 06:51:54 pm
content: The best place to start is probably the datasheet, this is a similar device in the series.https://www.latticesemi.com/-/media/LatticeSemi/Documents/DataSheets/ispLSI/ispLSI1024DataSheet.ashx?la=enIf the part is defective though there's a good chance you won't be able to read from it, and I would also expect it to be copy protected if it supports that.Is the game you're trying to repair supported by MAME? If so then somebody may have already worked out the function of that chip.

author: payty
author_rank: Contributor
timestamp: July 12, 2023, 06:09:46 pm
content: Yes, it is supported by MAME but the game ZIP includes some firmware for two smaller chips, gal20v8 I think.I know that it may be locked but I have nothing to lose by trying to copy. A chinese company asked me 2000$ for this.

author: james_s
author_rank: Super Contributor
timestamp: July 12, 2023, 06:50:23 pm
content: Is there a schematic for the board? If you know what the chip does, and you have the memory map from the MAME source then you may be able to treat it like a black box and write some code for a modern-ish CPLD or FPGA that does what that chip does. It's not easy but people do manage to do that.

author: Wiljan
author_rank: Regular Contributor
timestamp: July 13, 2023, 07:27:42 am
content: Found a manual for the REVOLUTION X here:https://manualzz.com/download/10612068It does have a PLSI1032 on page 93 "Main Ctrl PAL" as a part of the "Video CPU Board"On such old hardware, be sure to suspect bad connections on plugs, connectors, switches (even IC-sockets) due to corrosion.Also doublecheck the PSU for right voltages, ripple etc. (old caps)

author: Wiljan
author_rank: Regular Contributor
timestamp: July 13, 2023, 08:23:32 am
content: Here is a bit of information on programming the PLSI1032 on page 34 and forward also they do mention the Security Cell on page 31http://bitsavers.informatik.uni-stuttgart.de/components/latticeSemiconductor/_dataBooks/1992_Lattice_pLSI_and_ispLSI_Data_Book_Supplement.pdfIf you start trying to read out the chip, see if you can get hold on a 2. chip firstProgram the 2. chip with some test data and see you can read it out before trying read out the original chip.On page 39 you will see the state machine instructions for programming...If you send the wrong code the chip might be erased.On page 18 you can see 3.party programmers which does support the chip.I recall the Allpro from back that time, but I don't have any.If the Security bit is set, it might not be possible to get the data out

author: payty
author_rank: Contributor
timestamp: July 13, 2023, 08:44:00 am
content: Well I have three boards of the same game. The thing is that the signals I am checking right now trigger the OUTPUT_EN for some RAM and ROM chips. Those come from this ISP1032 chipand go through an OR gate together with rhe RAS signal.I have removed the chip that contains all OR gates so there is no interference with the output of the ISP1032 now.I suspect that this chip is bad ant not the board because I have switched the chips between boards and the behavior changes. There are three OUTPUT enable signals. One chip has floating values for all three,One just for one, and one for two of them. I check these signals with the oscilloscope direclty on the ISPLSI 1032 socket.Caps have been changed and I have checked the traces around them and everything seem to be ok.

author: payty
author_rank: Contributor
timestamp: July 13, 2023, 09:15:22 am
content: Quote from: Wiljan on July 13, 2023, 08:23:32 amThis is great info! Thanks. I will read it first.

author: james_s
author_rank: Super Contributor
timestamp: July 13, 2023, 05:27:10 pm
content: In an arcade game it is virtually certain that any security features offered by the chips will be used, cloning was a big issue in the early days and arcade hardware often uses tricks to try to thwart this or at least delay it until a game has gotten through the phase of being new and high earning.

author: chrysler333
author_rank: Newbie
timestamp: December 26, 2023, 02:14:49 pm
content: Quote from: Wiljan on July 13, 2023, 08:23:32 amthats exactly what happened to me. Be careful with that