[vcf-midatlantic] Heathkit H8
glenn.f.roberts at gmail.com
Fri Feb 5 15:54:29 UTC 2021
To manage my sanity (and spousal relations) I whittled my collection down some time ago to only Heathkit, primarily H8, because that was where I started with microcomputers back in 1981.
Mine are fast (10Mhz) and highly reliable and I use these actual systems (rather than emulators) to develop and test various software enhancements. The early models had tinned connectors on the buss/backplane which caused some reliability issues - Heath later went to gold plated, so if you have an early model it's best to replace those pins. Another source of reliability issues is old memory cards - I pretty much use modern RAM cards on any system I plan to use day to day. I’m told the first generation serial I/O card (H-8-5) sometimes had trouble at 9600 BAUD but the second generation board (H-8-4) and modern replicas are solid performers. Relying on the H17 floppy disks is also an issue - these are 10-hard-sectored media. But most of us have moved to soft-sectored/MFM drives and/or emulators like GoTek <http://www.gotekemulator.com/> or SVD <http://thesvd.com/> . For the rare occasion where we need an actual H17 diskette we have punches that can convert soft-sectored disks into 10-hard format.
The H8 had a unique passive cooling design (no fans) which can be problematic for a fully loaded chassis. Many of us have replaced the regulators on these boards with switching buck converters, which run much cooler. A popular early hobbyist enhancement to the H8 was to cut a hole in the side of the cabinet and add a boxer fan but the “purists” among us eschew such mutations! 😊
We have developed modern solid-state drives and USB/flash drive interfaces so floppy drives are essentially only needed only for reading archival disks from the occasional rescue mission.
The H8 has a unique and powerful front panel monitor that lets you monitor and change, in real time, any address or register. A very elegant design. The design was clearly influenced by “DEC think” – octal LED with an unusual “split octal” format, but subsequent updates to the front panel ROM added Hex support.
We also have full commented source code for Heath’s operating system (HDOS) and a full range of CP/M options including CP/M3 and some CP/Net capability.
> -----Original Message-----
> From: vcf-midatlantic <vcf-midatlantic-bounces at lists.vcfed.org> On Behalf
> Of Bill Degnan via vcf-midatlantic
> Sent: Friday, February 05, 2021 9:54 AM
> To: vcf-midatlantic <vcf-midatlantic at lists.vcfed.org>
> Cc: Bill Degnan <billdegnan at gmail.com>
> Subject: Re: [vcf-midatlantic] Heathkit H8
> I am interested in buying (or borrowing) an H8 at some point if the price is
> right to explore the model and its workings. I remember talking to Alex
> Bodnar about them, and I told him then I had always "avoided" this model
> but it must be a past life or something that has always caused me to avoid
> getting involved with the H8's. Are they reliable?
> On Fri, Feb 5, 2021 at 9:12 AM Glenn Roberts via vcf-midatlantic < <mailto:vcf-midatlantic at lists.vcfed.org> vcf-
<mailto:vcf-midatlantic at lists.vcfed.org> > midatlantic at lists.vcfed.org> wrote:
> > If there are any Heathkit aficionados in the VCF group that aren't
> > aware of "SEBHC" it's the so-called Society of Eight-Bit Heathkit
> > Computerists, which currently collaborates via a google group:
> > <https://groups.google.com/g/sebhc> https://groups.google.com/g/sebhc
> > pretty strong signal-to-noise ratio on this list, with typically a
> > handful of messages a day. Mostly 8-bit platforms, mainly H8 and H89
> > but the occasional discussion of Z100, H11 (LSI-11), ET-3400 or HERO.
> > Many former employees of Heathkit or associated small companies are on
> > the list; also a lot of previous DEC folks. The group maintains
> > several archival repositories of software and documentation and is
> > active in producing modern updates and enhancements to these classic
> > systems (see especially <http://koyado.com/Heathkit/Welcome.html> http://koyado.com/Heathkit/Welcome.html).
> > New SEBHCers welcome...
> > - Glenn
> > > -----Original Message-----
> > > From: vcf-midatlantic < <mailto:vcf-midatlantic-bounces at lists.vcfed.org> vcf-midatlantic-bounces at lists.vcfed.org> On
> > Behalf
> > > Of Herb Johnson via vcf-midatlantic
> > > Sent: Thursday, January 28, 2021 6:42 PM
> > > To: vcf-midatlantic < <mailto:vcf-midatlantic at lists.vcfed.org> vcf-midatlantic at lists.vcfed.org>
> > > Cc: Herb Johnson < <mailto:hjohnson at retrotechnology.info> hjohnson at retrotechnology.info>
> > > Subject: Re: [vcf-midatlantic] Heathkit H8
> > >
> > > It's good to see H8 activity. I have one but it's sitting quiet
> > > these
> > days:
> > >
> > > <https://www.retrotechnology.com/herbs_stuff/h8.html> https://www.retrotechnology.com/herbs_stuff/h8.html
> > >
> > > It is also "native" pretty much. I'd not mind a floppy controller
> > upgrade, but
> > > not too modern a board. I also have some early SEBHC H8 boards
> > > unbuilt, from quite awhile ago. Thanks for the reminder!
> > >
> > > regards, Herb
> > >
> > > --
> > > Herbert R. Johnson, New Jersey in the USA
> > > <http://www.retrotechnology.com> http://www.retrotechnology.com OR .net preserve, recover, restore
> > > 1970's computing
> > > email: hjohnson AT retrotechnology DOT com or try later herbjohnson
> > > AT comcast DOT net
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