External Drive Case

[Chris Davis]

Here's my progress so far.

I still need to print the front panel graphics and make some other tweaks.  I really like booting and using software from a diskette.  It's makes the whole experience more authentic.  David, the disk controller is really an amazing add-on, well worth the effort of sourcing the components and building.  Good job.

So back in the early days, did the disk drive come with a boot ROM, or were users expected to toggle in or load a boot loader from paper tape?

[John Kennedy]

Wow that's going to look wonderful! 

[Walt Perko]

Hi, 

It looks like if you turn the power supply up on one side and around, then you could have two half-height or one full-height floppy drive in the cabinet.    

That design could be expanded to an 8" full-height drive.  

I'm so jealous that I don't have access to a 30W+ laser cutter/engraver.  I loved making cabinets for stuff when I lived in Silicon Valley and had access to TechShop.  I used the Epilog laser cutter/engraver almost daily, and the desktop CNC Mill a few times.  I wish I had both machines in my apartment for making stuff.  

.

[Chris Davis]

Maybe a full height, but I'm not going to create the internal structure to accommodate two half-height drives.  BTW, are there any full height 1.2mb drives we can use with the controller?

[fridtjof.ma...@gmail.com]

"Back in the day"... Tarbell users may have been inclined to toggle in the bootstrap. MITS drive users... not so much. Either a ROM that "disappeared" one the first I/O (copy contents of self to RAM, and then go there). or the 2K PROM card.Martin Eberhardt has (published in deramp.com) the 256 byte boot ROMS. UBMON, HDBL, MBLE and CDBL. A whale-load in just 1K total. I am running

the four Eberhardt ROMs, and a 63K CP/M. I guess that "back in the day" it would have been 62K RAM/2K PROM . But I like the

extra 1K of RAM (for HiTech C). After the Altair, I had a Z80; coded a small 256 byte ROM that did enter/display/exec from terminal (in hex, not octal). Used that to enter the bootstrap for floppy (1791 I think) That, like the Tarbell boot, was 20 to 40 bytes of code. The MITS controller was a bear... took a lot more to read a sector from that beast! I guess loading a stage 2 boot from cassette or paper tape was possible, but I never saw that done... Instead, 1 or 2 K of PROM was popular -- "power on and boot from floppy" 

[Mark Lawler]

Noice!!!!

[Terry Fox]

A small correction:  Tarbell floppy controllers DID have boot roms that optionally come into play upon computer reset.  I have three machines (one IMSAI, one Altair 8800, and one Altair 8800b Turnkey) that all have Tarbell single density controllers and Shugart 800 eight-inch drives.  I also have a couple double density Tarbell controllers not currently installed.

Terry, N4TLF