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Messages - elmer

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Hardware / Re: Like a Z180, but much better ... the Z280
« on: Yesterday at 22:12 »
Have you read this thread about overclocking the EP?


I read it again, and if I am understanding it, any replacement CPU *MUST* use the clock from the Nick chip, or accesses to video memory will break.

It seems as though Zozo and you other hardware-experts have already tested and figured out how to overclock Dave with a 20MHz (or 16MHz) crystal, and so use a 10MHz (or 8MHz) CPU.

From my POV, I think that I prefer the idea of running the computer at 8MHz rather than 10MHz, because then all of Dave's audio register values just need to be doubled in order to get the correct frequencies for any game sound.

Somehow it also just seems like a more reasonable speed for CPUs in the late 1980s, when the Z280 came out.

From my personal curiosity, I wonder what an Enterprise-sequel could have looked like back in 1987-1989.

As soon as you get much further than those years, it was becoming clear that the IBM PC and its clones were going to take over the entire home-computer market. :ds_icon_frown:

Hardware / Re: Like a Z180, but much better ... the Z280
« on: Yesterday at 00:04 »
It runs on 5V, it has a Z80-compatible bus mode, and it offers internal clock-doubling!  :shock:

Oh dear, no it doesn't! :oops:

Wikipedia is wrong and it offers clock-division instead, so the CPU clock can be 1,2, or 4x the bus clock, but you've still got to give the CPU a higher clock speed.

That presumably means that it would need a board with its own clock, and then either feed that clock into the Enterprise motherboard, or directly tap the Enterprise's own 8MHz or 12MHz clock signal.

Hardware / Like a Z180, but much better ... the Z280
« on: 2021.January.19. 23:00:44 »
I can see that there are a number of threads where people have talked about putting a Z180 into an Enterprise ... but how about the Z180's bigger and better (but less successful) cousin from 1987, the Z280?

It runs on 5V, it has a Z80-compatible bus mode, and it offers internal clock-doubling!  :shock:

I didn't think that there would be any of the chips still available, but apparently there are still a *few* for sale.

Programming / Re: IS-DOS crash bug.
« on: 2021.January.15. 20:51:03 »
Here is the final set of changes to the IS-DOS 1.0 source to convert it to fully build with Z80ASM and SLRNK1.

The advantages of Z80ASM and SLRNK1 are ...

1) It is much faster than M80/L80.
2) There is no need to output the .REL files with different names to the .MAC files.
3) Labels are significant to 16 characters (rather than 6 in L80), allowing them to be more readable.
4) SLRNK1 can link to Page3 ($C000-$FFFF) without leaving Page3 unused in CP/M. This means that IS-DOS can now be built on an actual Enterprise!
5) SLRNK1 does not put a relocation header onto the output file, meaning that the output that it writes is directly usable as IS-DOS.SYS (i.e. there is no need to use SJASM to strip junk off the start of IS-DOS).

The only significant changes from the source code that I posted a few days ago, was to fix labels that were actually wrong, but worked OK with M80/L80 because the first 6 characters were correct.

I have included new builds of XCPM that use the full 64KB of Z80 memory, to take advantage of SLRNK1 not needing to leave $C000-$FFFF free for the linked program.

Programming / Re: IS-DOS crash bug.
« on: 2021.January.15. 20:30:31 »
Ok.... maybe I offended somebody, so I am going to explain me.

Haha ... I don't think that any English speaker would be offended by what you said! :)

For some of us, the imprecision of the English language is one of its charms, and it is the source of a lot of British humour. ;-)

Programming / Re: IS-DOS crash bug.
« on: 2021.January.14. 19:56:32 »
And you can make an EXOS/EXDOS program that can be run from IS-DOS or loaded as an EXOS program! https://enterpriseforever.com/programming/com-file-for-is-basic-and-is-dos/ :mrgreen:

Nice trick! :ds_icon_cheesygrin:

Programming / Re: IS-DOS crash bug.
« on: 2021.January.14. 19:30:58 »
May be we could edit more intelligible texts with more space available.

Yes, this is something that can reasonably be done ... as long as they don't all get much longer, and so use up a lot of extra space.

There are only about 320 bytes of usable space left in the current IS-DOS.SYS program file, and in where it actually runs when in memory on the Enterprise.

That really isn't a lot of space to play with, and I need most, or maybe all, of that memory to improve the performance and capabilities of the video driver, which is what I personally feel is the most-important thing to add to an IS-DOS version 1.1, because it directly effects the user-experience of running existing programs like WordStar, VEDIT and Turbo Pascal.

Beyond that, adding some MSX-DOS2 functionality (or CP/M 3, or Z-System) will need a major reorganization of how IS-DOS actually runs when it is in memory, and that is likely to break things and need a lot of work and testing to make it stable.

Please remember, from a programming point-of-view, you can already accomplish nearly all of this extra functionality just by using native EXOS and EXDOS calls within an IS-DOS program, or you can just write a native EXOS application.

Programming / Re: IS-DOS crash bug.
« on: 2021.January.12. 18:33:45 »
Here is the latest IS-DOS source, buildable with either Z80ASM or M80, both using the L80 linker.

Bruce's EXDOS3 changes are included, but currently disabled so that this corresponds exactly to version 1.0 of IS-DOS.SYS

For anyone that wants to track the differences, here is what I needed to change from the original files that Zozo posted ...

"FCB1" and "FCB2" were defined in both START.MAC and the private EXDOS CLIDATA.MAC.  I have renamed the IS-DOS ones, used in START.MAC/CLI.MAC/CMD.MAC.

"ORM" was defined in both CLIV.MAC and the private EXDOS CLIVAR.INC.  I have renamed the IS-DOS ones, used in CLIV.MAC/CMD.MAC.

All uses of the M80-specific "CODE" macro, which were used to either define self-modifying code addresses, or define single-byte opcodes used to skip over the next instruction (to avoid branch instructions), have  been removed and replaced with code and comments that work on both assemblers.

Most of the uses of "IF1" and "IF2" have been changed, since Z80ASM only needs a single pass to build the source.  There are a couple of files left that still use these, but they aren't critical to building a functioning IS-DOS.SYS.

I have included the Z80ASM.COM and SLRLNK1.COM in the archive, both configured (using their CONFIG programs) to default to ".MAC" source files and ".SLR" script files (which avoid the need to rename files to get around CP/M's 128-character line length limit).

There are also 32-bit and 64-bit Windows builds of the modified XCPM that works with Z80ASM, together with a patch file for the changes from the current version of lgb's "ReCPM" project on github.

Enjoy! ;-)

Programming / Re: IS-DOS crash bug.
« on: 2021.January.12. 17:49:14 »
It is have a 3x16K at the segment 04-06h.
07h are special segment: it is a ROM and RAM and memory paged I/O. ROM are 8x8K pageable. In the current version with EXDOS 1.4 only the first 8K page used, but the new EXDOS 3 will use more pages, for store ISDOS and others.

Excellent, that is a very nice piece of hardware that SzörG created! :cool:

Interface / Re: Internal memory expansion
« on: 2021.January.12. 17:41:15 »
I only have 2 of the 512KB memory expansion boards left, if there is anyone else out that that wants to add some memory to the Enterprise 64 that they recently bought from Egypt or Russia. ;-)

Programming / Re: IS-DOS crash bug.
« on: 2021.January.11. 20:24:17 »
Here are two slightly modified files...could you incorporate them into your "IS-DOS 1.1" source please?

Absolutely! :)

BTW SD Card versions of EXDOS 3 will have ISDOS.SYS in ROM! :roll:

That will be cool, there are a few improvements that can be made if IS-DOS is either in ROM, or in a RAM extension.

Having it as a RAM extension is probably best, even on a 128KB Enterprise, so that it can just page in its runnable self-modifying code as needed ... but I do understand that you've got enough spare space in a 32KB EXDOS to store 11KB-or-so of compressed IS-DOS code.

As for the SD Card ... is there enough space in the SD Card ROM for a 32KB EXDOS???

From my quick look at the SD Card ROM files, it *seemed* like there is only about 24KB of space for EXDOS and the SD Card driver code, unless you start using the 32KB that is currently used by the BASIC ROM and a language ROM.

Programming / Re: IS-DOS crash bug.
« on: 2021.January.11. 19:17:21 »
There is a time for version 1.1!

Hopefully you'll give me the time to add the faster video code into the source files! ;-)

I am currently modifying the IS-DOS source code to build with the SLR Z80ASM assembler, which is about 99% compatible with M80, but runs much, much faster.

The changes are done, and the source builds, but now I just have to figure out a linking issue.  FYI, the source still builds fine with M80, the changes really are very minor.

I had to add 2 new fake BDOS function-calls to XCPM to get Z80ASM to work ... do you gentlemen want a patch file for lgb's ReCPM source?

Programming / Re: IS-DOS crash bug.
« on: 2021.January.10. 20:40:32 »
There is a crash bug in IS-DOS, probably introduced sometime between when the IS-DOS specification document was written, and the final IS-DOS version 1.0 was released.
Now it isn't very difficult to patch IS-DOS to fix this bug, but I don't see it as being worthwhile unless someone is patching IS-DOS for other reasons.

Returning to this, now that we have the original source code, the bug is in the source file CLI.MAC, line 854 ...

Code: [Select]

It should be ...

Code: [Select]
NOMEM: LD E,0 ; Move IS-DOS down to page 0.

Following up on VEDIT ... I have found my archive of the original VEDIT 2.31b Master Disc, complete with the modified terminal files for both the Enterprise and Amstrad CPC, and the original source code to my patch.

What is also interesting about this distribution of VEDIT, is that there is a lot of useful extra documentation about how to customize the program, that isn't included in the Ted Green's public release of VEDIT 2.33b.

Enjoy! :ds_icon_cheesygrin:

Programming / Re: IS-DOS crash bug.
« on: 2021.January.10. 17:51:24 »
lgb: https://enterpriseforever.com/profile/?u=6

Cool! :)

I suspected that he was active in the community here once I saw his location, and that he had developed an Enterprise emulator.

The .REL files do not have to have the same base name as the source files, and back in the day (and still for EXDOS 3) we would assemble the sensibly-named .MAC source files to a less-sensibly-named two letter .REL file, for example START.MAC would assemble to ST.REL, REBOOT.MAC would assemble to RE.REL etc to shorten the L80 command line length!

Hahaha ... nice workaround for the problem, much better than using lib80!

I've applied that trick and have got IS-DOS building with just simple XCPM calls.

I am not surprised, XCPM is very hacked together by lgb and he did warn us that not all functions are supported! :roll:

Now that I can see the source code and understand what it is doing ... it is a very, very nice solution to get the old source code building on a modern computer!

I like having RunCPM too as an alternative, the critical thing with both of them being that they just accesses files on your regular PC, and that there is no need for using disc images.

That keeps the source editable with modern editors, and usable with "modern" tools such as grep/diff/patch.

It also allows using Source-Code-Control systems such as GIT or PERFORCE, which might be cool is you get to the point of having multiple people working on code, or want to keep a formal log of the changes that are made.

SCC is something that us programmer-types didn't ever really have to think about in the 1980s, but is such an important part of modern software development.

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