Recent content by BillGee

Well, I just tried and failed to install DOSBox-x on a Raspberry Pi. DOSBox, on the other hand, was a simple "sudo apt install dosbox" away. <rant> That is something I sometimes detest about open source. While you can build it from source code, sometimes they MAKE you build it from source...

It is for playing games only. Game developers have a use for a place to write debugging messages...

For the longest time, I used DOSBox. My main application is to use it to develop DOS-based programs using Borland tools. I have tried in vain to find a way to write debugging messages to the console/status window. Others have asked on the 'Net, but no solutions. Then I discovered that...

Start with Mike Douglas: https://deramp.com/swtpc.html https://www.youtube.com/@deramp5113/videos Also search the 'Net for 68 Micro Journal

Are you living in D/FW now? I bought and built a Replica I at a VCF at the Computer History Museum in Mountain View many moons ago. Somewhat recently, I bought an Altair Micro from someone else. Unfortunately, it did not come with the memory and "disk" board so I cannot run CP/M. One thing I...

Are you Raymond J from DMS and VECTOR? I never would have guessed from your user name.

Amiga, Atari ST, 1st gen Palm PDAs, PT-68K and Sun plus many other UNIX boxen would argue otherwise...

The IEEE 754 floating point standard was widely accepted because there was a real need. The assembly syntax one was not necessary and having to pay for the document did not help.

Worse than that, it has led to bugs which were difficult to detect. There was a case in FLEX when something like ldaa $45,X assembled as ldaa $45 because a space was typed by mistake before the comma. Requiring a comment to start with a special character would have caught...

Well, I remember programming Pascal on a mainframe and using: (* for { *) for } (. for [ .) for ] My last guess is that assemblers at the time had rudimentary expression evaluators. Strictly left to right with no operator precedence and parenthesis cannot be used for grouping. So there was...

OK, let me try again then. Much of the early microprocessor software was done using a cross-assembler running on an IBM mainframe. EBCDIC does not have those characters.

The 6502 and 68000 also had this problem with their indirect modes. My guess is that teletype machines and early terminals do not support '[' and ']' characters. The best way to handle this is for the assembler to expect an indirect addressing mode specification when it encounters a '('...

For CP/M work, if the decision was made to produce a program compatible with the 8080/8085, there is a distinct advantage in sticking with 8080 mnemonics - you cannot accidentally use a Z80-only instruction. When Intel made the transition from the 8008 to the 8080, they decided to stop using...

With a few exceptions like the alternate register set, the "new" Z80 instructions were slow for what they did, mostly due to the cost of fetching an additional opcode byte. The cost to get an address into an index register sometimes negates the benefit of using them. Many CompuPro machines...

6800, 6502, 6809 Around 1980, First Texas Savings aired a TV spot featuring three masked thugs and the theme, "we will help you beat the 80's." I would joke that those baddies were 8080, 8085 and Z80 as I was mostly a 6800 and 6809 guy at the time.