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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
07131 Graphics Minor Always 24 days ago 19 days ago
Tester nippur72 View Status Public Platform
Assigned To Resolution Open OS
Status [?] Driver vtech2.cpp
Version 0.202 Fixed in Version Build
Summary MESS-specific 07131: laser500: charset ROM is wrong (and I fixed it)
Description the charset ROM for laser 350/500/700 referenced in MESS was originally drawn by hand and does contain many errors. For example the "D" and "m" have a different graphics than the real machine.

I've fixed such errors for a Laser 500 emulator of my own, but I cannot use in MAME/MESS because of the different CRC.

I enclose the fixed ROM file, but I don't know exactly how this will be handled since MAME/MESS does not ship rom files...
Steps To Reproduce
Additional Information
Flags
Regression Version
Affected Sets / Systems laser500
Attached Files
jpg file icon example.jpg (90,071 bytes) 24 days ago Uploaded by nippur72
nippur72
zip file icon laser500.charset.rom.zip (1,906 bytes) 19 days ago Uploaded by nippur72
charset ROM dumped by Tonino Bisazza, 02-nov-2018
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Notes
5
User avatar
No.15642
nippur72
Tester
24 days ago
sorry, the submit form attach file function is bugged and caused #7129 and #7130 issues to be opened. They can be deleted.
User avatar
No.15661
hap
Developer
23 days ago
Did you dump the rom chip, or did you correct the graphics manually by comparing to the real Laser 500?
If it was dumped, is the size correct? MAME's source says this rom is a TMS 2364-25NL (aka 8KB)
User avatar
No.15706
nippur72
Tester
19 days ago
No I did not dump it, I just manually corrected the graphics comparing to the real machine.

Yes the ROM is an 8K, on the Laser 700 it's a "TMS 2364-25NL", on the Laser 500 it's an EPROM labeled "ZA234015".

Looking at the schematic diagram of the 500/700 it seems that not all pins are directly connected, only A0-A10 go straight to the video chip, A11 and A12 are driven in a strange way I don't understand.
User avatar
No.15712
Robbbert
Developer
19 days ago
You can use it in MAME/MESS if you rename your file to the same as the original one, and then you run MAME from the command line.
User avatar
No.15714
nippur72
Tester
19 days ago
UPDATE: I managed to get a real dump for the charset ROM. Tonino Bisazza extracted it yesterday from a working Laser 500.

I deleted the manually created file and substituted it with the the correct one named "laser500.charset.rom.zip".

Tonino Bisazza said he dumped the ROM as if it was 16K sized eprom, but only the topmost 8K contains data, suggesting it's actually an 8K eprom.

Previously unknown, the ROM contains ENGLISH, GERMAN and FRENCH charsets at different offsets that are enabled by hardware switches (presumably when they customized the machine for different countries along with the QZERTY keyboard layout). The circuit diagram shows two switches corresponding to A11 and A12 lines in the ROM.

Another difference from before is that the graphics in the ROM is flipped horizontally: the most significant bit is the rightmost pixel in a row, not leftmost.