fred@cbmvax.cbm.UUCP (Fred Bowen) (12/13/86)
1541B DOS ROM RELEASE NOTES
Commodore Electronics, LTD. 5 December 1986
1541B ROM RELEASE NOTES: 251968-02 (16K byte, 300ns, checksum=$1A69)
THE FOLLOWING MODIFICATIONS HAVE BEEN MADE TO THE 251968-01 ROM CODE TO
CREATE A NEW ROM RELEASED ON 12/05/86. THIS RELEASE IS MADE TO CREATE
MASKED ROMS FOR PRODUCTION OF THE 1541B/C MODEL DISK DRIVE ONLY.
1. The interrupt rate change from 15 to 8ms for slightly better
performance caused compatibility problems with some software
that used that timing for its own purposes. It is now 15ms.
2. The 1541B board has troubles accessing tracks beyond 35
attributable to the new data separator, although the problem
always existed (wrong bit cell densities because TRKNUM only
listed up to track 35). TRKNUM has been extended.
3. SAVE-@ (SAVE with replace) is fixed. The variable NODRV is
now a 16-bit addressable var, and the STLBUF routine steals
the buffer locked by drive one.
4. Relative File fixes (unspecified).
5. Serial bus (DEVICE NOT PRESENT) fix. TSTATN now clears IRQ.
6. Block read fix (unspecified).
7. Write to stack area bug (unspecified).
8. Set decimal mode (SED) before disabling IRQ (SEI) fixed.
9. Disk full bug (unspecified).
10. Add copyright notice for legal types and thieves.
11. The ROM checksum adjustment byte at $C001 is now $46.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
PLEASE NOTE: THIS ROM WILL _NOT_ WORK IN EARLIER 1541 PCB'S, WHICH REQUIRE
DIFFERENT SIZED ROMS (8K), AMONG OTHER BOARD DIFFERENCES!
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
--
Fred Bowen uucp: {ihnp4|seismo|caip}!cbmvax!fred
arpa: cbmvax!fred@seismo.css.GOV
tele: 215 431-9100
Commodore Electronics, Ltd., 1200 Wilson Drive, West Chester, PA, 19380