Engineer Dr. Scott M. Baker has expanded his work with bubble reminiscence know-how, constructing a Zilog Z80-based single-board laptop which makes use of the Nineteen Seventies non-volatile storage as its working reminiscence — and a RC2014-compatible multi-board design beside.
“I believed it will be enjoyable to construct the minimal attainable laptop that supported bubble reminiscence storage, and so I developed a small Z80 laptop with bubble reminiscence, operating BASIC because the programming surroundings,” Baker explains of his newest challenge. “The board was simply ported for use on the RC2014 laptop.”
The one-board laptop Baker has created builds on his earlier work constructing a storage card for the Heathkit H8 microcomputer utilizing the identical bubble reminiscence know-how — initially launched within the Nineteen Seventies as a non-volatile storage which operates by the migration of magnetic ‘bubbles’ round a patterned substrate. Whereas the reminiscence board merely added 128kB of storage to an current laptop, although, Baker’s newest construct locations it on the coronary heart of a completely new design.
“Everybody who has designed or constructed a single board laptop within the final decade or so has heard of the RC2014 and/or of Grant Searle’s Z80 laptop,” Baker notes. “The RC2014 in its most elementary for is a straightforward Z80 laptop with 32k of RAM and as much as 32k of ROM. Different combos are attainable, 48k RAM with as much as 16k of ROM, and even paged RAM/ROM configurations providing a megabyte or extra of mixed storage. RC2014s can run BASIC, CP/M, Fuzix, or a number of different choices. To design my single board laptop, I adopted an analogous strategy.”
The ensuing system makes use of a Zilog Z80-compatible processor, retaining compatibility with the identical BASIC port as used within the RC2014, and splits the deal with house cleanly down the center with 32kB of RAM and 32kB of ROM. “I truly solely want about 10kB for the Bubble BASIC interpreter,” Baker admits, “nevertheless it’s best to simply lower the deal with house in half.” Elsewhere on the board is a Zilog Z8530 Serial Communications Controller (SCC), providing two serial ports and an built-in baud-rate generator, and a GAL22V10D programmable logic machine for glue logic.
Baker has additionally designed a model of the board which connects to an RC2014 microcomputer package. (📷: Dr. Scott M. Baker)
The bubble reminiscence, an Intel 7110 module, acts as neither RAM nor ROM however as a readable and writable backing retailer for the machine — providing storage for user-written applications that will not be erased when the system is shut down, and with out the necessity to join a tape drive, floppy disk, or different exterior storage machine. The RC2014 variant, in the meantime, makes use of the identical bubble reminiscence however with out the RAM, ROM, and CPU, with the intention to create an add-in board appropriate with any RC2014 system.