M-Slot by Wilco/gflorez

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Computers converge

The 80s decade of the last century was very active in creative computer ideas. Some factors converged so that,for the first time, these ideas turned on possibilities for the masses, due to the existence of "cheap" microprocessors and memory, and the crescent demand impulsed by a society avid of new ways of enjoyment and the pressure on the media, universities and schools(and finally on the families) over the need of computer knowledge on the next paradigm of economy that menaced to sweep away our old way of life...

The 8-bit era of processors was nearing to its end so, the cheap micro-computers that were going to invade us where all based on the trusty Z80, heir of the 8080 and the not far times of the CP/M on business offices, or on the new contender, the 6502 and family, ancestor of the Risc processors we all have on our phones...

The Z80 was at large the most installed microprocessor on that era, due at least to two historical events: The creation of the MSX standard of computers and the Sinclair ZX Spectrum and Amstrad CPC success.

Internally all the Z80 based computers work the same: 3-4MHz of processor frequency, 64KB of memory range, some form of memory pagination and an 8-bit Data bus to access the peripherals.

Being son of his time, our Enterprise computer shares the same Data Bus as its contemporaries based on the Z80 microprocessor.

Years of hobbyist scene

The MSX computer series were manufactured during a decade, up to the beginning of the nineties of the XX century, always with the same cartridge slot pinout.

When the official support ended, groups of European hobbyst maintained the hardware flame of the MSX computers, creating memory expansions(Ram/Rom), serial cards or IDE controllers. The most famed was Sunrise, which was responsible of incredible expansions more suited for 16-bit computers, like its GFX9000 graphics cartridge, or the Moonsound Yamaha OPL4 cartridge. At its time these expansions weren't well received by the general MSX owner, still stuck on the poor MSX I specifications.

On the CPC side, groups of European owners have been active all these years, but not at the same hardware level, probably due to the numbers of different models and makers and incompatibilities between them.

The Enterprise scene is the most humble and unknown, because it is almost circumscribed to Hungary although, due to being basically only one model, every new made hardware was compatible with all the units.

On recent times there is an increased interest on that sweet era of 8 bit computers, and so, a lot of owners have rescued their forgotten jewels. New loading systems have surfaced, like Compact Flash or SD cards, and also Floppy or tape emulators. All the three systems are awaiting the last and definitive All in One card.

Making it exist

The disconformity with the high resources required to make work a WIMP system(Windows, Icons, Menus, Pointer) on a PC impulsed Jörn Mika, from now on Prodatron, to write a Graphic Operative System, SymbOS, for his Amstrad CPC with all these characteristics, to show that it was possible to do the same on a computer without so many resources.

Later he was tempted to port the software to other Z80 computers, the MSX and the Amstrad PCW.

It was a clever approach, even being computers with very different graphics and memory paginations, the programs made for SimbOS worked on the three platforms the same.

He himself was one of the developers of the all in one Symbiface interface for the CPC range, supported on SymbOS.

Then, Prodatron contacted with Enterprise-Forever, or was it the contrary?

He asked how the Enterprise worked inside, to see if it would be possible to make a port. Then he agreed to do it[1].

Actually the Enterprise has a marvellous SymbOS 3.0 port(minimum compatibility between all the systems), and the next phase(3,1) will be when it will take advantage of the individual characteristics of every computer series.

Returning to the old days of Sunrise releases, Prodatron was one of the few developers that supported their high end cartridges on his then, new operative system, on the MSX port.

But it happens that this current retro fashion has caused a great demand on these luxurious cartridges. So much so that, in various parts of the world, amateur groups have cloned and improved these designs, making them affordable for the general owner.

To who have been following the SymbOS thread on the Enterprise-Forever web page, it is now clear that Prodatron have in some form predicted that a MSX cartridge would be easily interfaced to a Z80 based computer like the Enterprise.

He had recently commissioned to the Brazilian MSX group the construction of a Yamaha V9990 based graphics card for the CPC range of computers, and at the same time he has commissioned Hans, from TMTLogic, the development of a MSX adapter for the CPC. Due to these events, now there is a V9990 version of the CPC port of SymbOS.

Then I asked me(gflorez): can it be possible to do the same on an Enterprise?

But first of all I had to create the conditions to make it real. Generally, on almost all Enterprises, the expansion connector is taken by the EXDOS controller, so we needed a way to connect more than one expansion there. A valid solution was created long time ago by Gyula Mészáros, but I was unable to find one of these Bus Expanders from my country, Spain. So I decided to make copies of his design, but on modern and, as cheap as possible, technology. You can find information about it on this link[2].

The Enterprise M-Slot approach