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Just a few words about the +3ROM ...
(i) The original +3B ROM v4.1
You should know by now that the original, first released +3, had many problems with the +3BASIC.
Ian Collier has an exhaustive document, The Canonical List of +3 Oddities. The document applies to the first +3 release, equipped with ROM v4.0.
I have not checked each address reference of that document in respect with the ROM v4.1. This is a difficult task, as the new ROM has been reassembled (by Amstrad) and almost all address reference from ROM0 and ROM1 is shifted.
Some of the bugs are still present. For example (with reference to Ian Collier’s document), the one from address #01D7 and #022F in ROM0. Or address #0769 in ROM1. Or the example 6.
However, there are, for sure, some bug fixes. I am aware of a few of them:
- (v4.1) fixed: the parallel printer port
- (v4.1) fixed: the SPECTRUM command (go into 48K mode)
- (v4.1) fixed: error messages address table is now complete, including the reference for “You should never see this” and “Hello there!” messages
(if ever need it, the error messages address table reference begins at address #2705 in ROM1 v4.0, at address #2873 in ROM1 v4.1 english version and at address #2881 in ROM1 v4.1 spanish version; for example, Tasword 3 for +3 makes use of this table, see its page for details)
- (v4.1) fixed: the buffer used by the COPY command, starting at address #ED11, is now located in page 7
But, they introduced a new bug:
- (v4.1) new bug: involves disk copying commands; in case of any error (say, write protect on destination disc, but can be anything else) the error message shown is "Drive not ready"
If anyone is interested in this ROM version:
The archive contains two ROM packages:
- the ROM for physical +3 (2*32K files)
- the ROM suitable for direct use with the X128 Spectrum emulator, just for testing purpose (4*16K files, found in directory X128)
I also have the original +3B ROM v4.1 spanish version. I can make it available for download, if anyone need it. Just let me know.
(ii) A modified ROM v4.1
Today I am using a slightly modified version of ROM v4.1.
This ROM is available in two versions, of which one has 4ms head stepper motor timing. If you have replaced your original Amstrad 3” drive with a 720K 3.5” one, or are using two 720K 3.5” disk drives, then using this version will greatly improve the disk access speed under +3DOS environment.
Notable changes:
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A new look ...
Because of the 50Hz TV screen flicker, the white background was irritant
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fixed: the new bug mentioned above, introduced with ROM v4.1
- change: the +3BASIC interface colors have been changed to blue background and white font (same as default colors on CP/M Plus for +3)
- minor change: formatted disks with the +3BASIC format command have now interleave factor 3 (however, the format command is still limited to 180K disk capacity)
- fixed: the disk catalog; irrelevant for normally 3" disk users, but important for 3.5" disk users, where more than 64 directory entries on disk were not displayed
- fixed: the duplication of two disks (COPY"A:"TO"B:" command) is now compatible with 720k disks, if both A: and B: drives are of 720k type
- fixed: the "COPY" command will give a full printer screen copy (all 24*8 lines, not only 22*8)
I have not given any new name to this +3ROM version. The blue background is enough for me to differentiate between two different ROM equipped machines.
The archive contains three ROM packages:
- the ROM for physical +3 with only 720K 3.5” drive(s) in use (either A: or B: or both); it gives faster disk access (2*32K files, found in directory 04MS)
- the ROM for physical +3 with the original Amstrad 3” disk drive in use (either A: or B:), that may also have a 720K 3.5” drive connected (2*32K files, found in directory 12MS)
- the ROM suitable for direct use with the X128 Spectrum emulator, just for testing purpose (4*16K files, found in directory X128)
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Note: there is only one variable for head stepper motor timing for both drives; it is not possible to have one drive with one timing and the other drive with a different timing
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Important: DO NOT use the ROM from 04MS directory on a +3 that may still use the original Amstrad 3” disk drive !
The only difference between the ROM from the 04MS directory and the 12MS directory is the head stepper motor timing - 4ms for 720K 3.5” drives and 12ms for Amstrad 3” drives.
The timing may also be modified via software (running a program, look at the John Elliot site), however, the software must be re-loaded after each reset and it should not be used if the Amstrad 3” disk drive may be in use.
Please note that if the Amstrad 3” disk drive is connected but not in use, the use of 4ms head stepper motor timing has no undesired effect on the 3” drive.
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(iii) The +3e
The latest development regarding the +3 ROM can be found on Garry Lancaster’s section at WOS site, The ZX Spectrum +3e. This is an ambitious project to add support for a hard disk to the +3 (or +2A) computers.
As far as I know, the +3e ROM is based on the original ROM v4.0 supplied with the first +3.
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