The Rompak cartridge system is an excellent low cost accessory for any ZX/TS user. The cartridge is a plugin EPROM read board with an expansion port for your RAM pack or peripherals. It also sports a neat ZIF socket.
The documentation is adequate although no schematic is supplied. The board is simple (about three parts) and easy to figure out. It is an uncased, but professionally built board that plugs solidly into the computer.
The cartridge is mapped to the normally unused 8K-16K block of memory, using an LS138 chip and, interestingly enough, a transistor. It reads not only the 2764 (8K) and 2732 (4K) EPROMs, but also, unlike other boards, the slower, cheaper 450ns ones.
A unique feature of the board is its ZIF (zero insertion force) socket. This device grips and releases the EPROM with a flip of the lever — no wrestling the EPROM in and out. No read board should be without one!
To support the board, Rompak also markets a respectable variety of software on EPROMs. Much of it is licensed from third parties. The quality is good to excellent at bargain prices. You pay cassette tape prices and get instant loading EPROMs. Instead of the usual cassette loading ritual, you need only type in a single command and have the program run instantly.
The first EPROM I tried was an arcade game called Timeblasters. 1t ran instantly with the command RAND USR 8243 which calls the MC routine that stuffs a block of EPROM memory into the ZX/TS memory where it begins execution. Surprising speed and graphics highlighted this addictive game. After several fleets of enemy craft had been destroyed, I turned to some practical software.
Changing EPROMs in the ZIF socket was a sheer delight. Mathpak performs plotting of functions, integration and differentiation of functions (with replotting), curve fitting of points, and solving simultaneous equations. The program is menu driven and highly interactive. However, the plotting routine is only the standard 64 x 44 PLOT resolution. In all, a really useful program, but really nice because it is instant.
The main disadvantage of the system, though, is that it does not quite eliminate the cassette. There is no way to store a program that you have written onto the cartridge unless you possess an EPROM burner and some machine code skills. EPROMs are available with MC routines that increase the speed of SAVEing and LOADing up to 15 times. Also several companies sell EPROM toolkits, compilers, assemblers, and other utilities. Although other EPROM read boards are available, I have not found any to touch Rompak’s low prices.
After using the system for about six months, I would definitely recommend the Rompak cartridge system as an inexpensive and painless way of entering the world of software on EPROMs.