david@ssc-vax.UUCP (David Norris) (01/05/84)
Help! Can anyone tell me if CP/M can run on the Model III with or especially without hardware mods? Or do they have hardwired ROMS? I will be teaching a Z80 course shortly, and want to use the better assembly language tools available under CP/M instead of garbagedos or flakedos. Since we have 15 such machines, purchasing "CP/M upgrade boards" for them all is out of the question. Any help appreciated. -- David Norris -- uw-beaver!ssc-vax!david
towson%amsaa@sri-unix.UUCP (01/09/84)
From: David Towson (CSD) <towson@amsaa> David - The TRS-80 Models I and III can run "remapped CP/M" with a transient program area beginning at 4300H instead of 0100H (the standard location). Lifeboat Associates has (or at least had) such a version of CP/M, and FMG Corporation (still in business?) did too. Some Heath computers also use this arrangement, so if you cannot find a TRS-80 version for sale, you can probably hack the Heath bios to work on a TRS-80. At least two companies, Omikron and Memory Merchant, sell memory remappers that shift read/write memory down to location-zero, thereby allowing the use of standard CP/M. The last price I heard was $130 for the Omikron device plus CP/M. The same companies also offer two options for dealing with the TRS-80 ROM. The remapping rolls ROM up to address C000H (in a 48K system). The Omikron system (I don't know about the other) overlays part of the TRS-80 ROM address space with their own ROM which contains the system initialization code and part of the bios. You can just ignore the remainder of the ROM address space and write it off, or you can get a RAM board that is addressed to that area, making that address space usable. If you cannot find a source of "remapped CP/M", but you wish to go that way, contact me again and I'll try to help. Dave Towson towson@amsaa
towson%amsaa@sri-unix.UUCP (01/09/84)
From: David Towson (CSD) <towson@amsaa> I agree wholeheartedly with the comments from decvax!genrad!john@ucb-vax concerning the goodness of TRS-80 operating systems such as NEWDOS80 and LDOS. Those two operating systems are quite sophisticated. They offer all of the features of standard CP/M, allow a degree of I/O redirection, will support all sorts of disks, and will search all available disks automatically looking for a requested program. You can also switch disks at will for read or write without incurring the maddening abort "BDOS ERROR R/O" which CP/M'ers have come to hate. Both of the OS's mentioned are well supported, and there is a large available software base. The only caution that I would offer is that, unlike CP/M programmers, those for TRS-80 dos'es are not as well disciplined about doing I/O through the operating system. The result is that direct control of the disk controller, and to a lesser degree direct reading of the keyboard make programs written for the Model I unusable on the Model III (those programs that are written using direct control, i.e., not through the dos, that is). But the two operating systems mentioned are quite good. I have worked with at least 11 different operating systems for the Model I (which is what I have) including both base-0 and base-4200 CP/M. I spent several years using non-CP/M dos'es. I now use CP/M almost exclusively for the simple reason that there is a huge amount of good, free software available for the downloading via the Defense Digital Network. I guess a secondary reason is that I get myself all wrapped around the axle when I switch dos'es after not using one for a while. (Yester- day, I even had to think a minute to remember how to enter a NEWDOS copy command for a disk backup.) Finally, the above writer's comment concerning the non-usability of CP/M programs written for a base-0 environment when you have a base-4200 (remapped CP/M) system is an important consideration. Fortunately, the public domain software generally comes with source code, and can be re- assembled for the different bases. Many programs even have assembly switches built in. However, one cannot assume that all programs will have source code available to the public. This is particularly true of the most desirable commercial programs. In choosing between a TRSDOS-like dos and CP/M (either remapped or standard), one would be well advised to investigate the cost and availability of the particular needed applications software as well as the other obvious costs. Dave Towson towson@amsaa
kevinw%isl@BRL.ARPA (01/13/84)
in cpm+ you may freely exchange disks in between files without resetting
the filesystem -- but i don't think any system will let you change disks
while you have files open (and try to read/write afterwards).
cpm plus is much better than cpm, although there are some minor incompatibilities
with command names/features... oh, well, such is progress.
-- Kevin
kevinw@su-dsnz011@dalcs.UUCP (Colin Pye) (01/18/84)
. In the March 1983 issue of 80 Micro, there is an item on a "$5 CP/M modification". The item, by Bill Brewer details how to make a 2 chip change to accommodate the low memory requirements of CP/M. I also suggest that this discussion be moved to net.micro.trs-80, after all, that's what it is there for. (Take note, Comodore 64 owners, there is a net.micro.cbm) -- _______ | O | From the disk of | o | |_____| Colin Pye Net address: ...{utcsrgv,dartvax}!dalcs!z011 Where in the world: Dalhousie University Halifax, Nova Scotia