64K RAM Ought to be Enough: a demo for the PCjr

Updated 2018–10–08 A demo for the IBM PCjr by Pungas de Villa Martelli. It was presented at Flashparty 2018 and won the Demo category. Requirements An IBM PCjr with at least 64k RAM. Download Source code: https://gitlab.com/ricardoquesada/pcjr-flashparty–2018 Binary:pvm-64ko.zip (does not run on emulators) Technical description The demo is divided in the boot loader and demo 3Continue reading “64K RAM Ought to be Enough: a demo for the PCjr”

Performance of the 8088 on PC, PCjr and Tandy 1000

It’s well-known that you should measure the performance of your code, and not rely only on the opcode’s “cycle counts”. But how fast is an IBM PC 5150 compared to a PCjr ? or to a Tandy 1000? or how fast is the Tandy 1000 HX in fast mode (7.16Mhz) compared to the slow modeContinue reading “Performance of the 8088 on PC, PCjr and Tandy 1000”

IBM PCjr: Zero-day Data-destroy vulnerability

IBM PCjr zero-day data-destroy vulnerability (AKA: Joykill). Description: This vulnerability allows local and remote attackers to destroy the contents of the floppy diskette. User interaction is required to exploit this vulnerability. The issue results from the lack of proper validation when starting the manufacturing system test. Exploit (local):

IBM PCjr BIOS dump

The IBM PCjr BIOS is very well documented in the IBM PCjr Technical Reference manual (a must read for every PCjr developer). The only problem is that navigating that code is not easy. It has all the problems from scanned books: the fonts don’t look good no hyper-links and difficult to search So I dumped theContinue reading “IBM PCjr BIOS dump”

Tandy 64 Jr. – an intro for the IBM PCjr

Happy new year! We (PVM) ported our Tandy 64 intro (originally designed for the Tandy 1000HX) to the IBM PCjr. Requirements: IBM PCjr. with 256k RAM Download: Binary: tandy64jr.zip Source code: https://github.com/c64scene-ar/tandy64/tree/ibm_pcjr Worth mentioning: Runs flicker-free Stable raster-bar, without garbage (world-first?)