80-Bus News

10

The format of the Boot command is now as follows:–

B Boot drive A, double density, sector 0, 5.25 inch or B sscd Where sscd is a single hexadecimal value.

Leading zeroes may be omitted. ss is the physical sector number to be read. Normally this is 0 or l. c is the command digit which has the following possible values:– 0 5.25 inch, double density 1 5.25 inch, single density 3 8 inch, single density

d is the drive select digit which has the following possible values:– 1 drive A 2 drive B 4 drive C 8 drive D

Examples of the enhanced Boot command

B 2 Sec 0, 5.25 inch, DD, drive B

B lll Sec 1, 5.25 inch, SD, drive A

B 134 Sec 1, 8 inch, SD, drive C

PATCHES REQUIRED First make the patches to bring V2.0 to V2.1, if needed.

Address V2.0 V2.1 F068 30 31 F108 20 ED F109 04 Al FIOA ED 20 F10B 4l 02

Then make the patches to bring V2.1 to V2.3.

At F068 change 31 to 33 At FBO8 change 3A 60 00 to CD EF FF At FCO3 change 11 99 FC to 3D 20 FD At FC11 change 20 27 3E DO CD 8C FC 3E O1 D3 E4 36 5B to 11 99 FC 20 24 3E DO CD 8C FC CD DE FF At FC42 change AF D3 E2 to 00 00 00 At FFDE there are FF characters to the end – change these to 3A 61 00 B7 20 01 3C D3 E4 3A 62 00 D3 E2 3E 5B c9 3A 60 00 B7 20 06 21 00 00 22 61 00 FE 02 DO AF C9

These changes have been carefully checked and the results fully tested, so you should have no difficulty. You can check that you have typed in the changes correctly by using the standard CRC calculating program. For your convenience this program has been run separately on the first 2K of RP/M V2.3 (CRC = EF 24) and the second half (CRC = 58 CD). Therefore you can easily confirm that your new RP/M 2.3 is correct. The CRC calculating program is called CRC.COM and is the subject of another article in this issue.