16KB RAM expansion on Apple //e

This card is not for Apple IIe. The Apple IIe already has 64K RAM on the motherboard.

No, it cannot work in an Apple IIe.

To add info...  16k RAM cards for a ][+ are designed to work in slot 0.  The //e has no slot 0 because the 16k RAM card functionality is built into the motherboard (also true of some later clones with 64k on the motherboard).  Also most 16k RAM cards require a jumper to a 4116 socket for DRAM refreshing.  The //e does not use 4116 DRAM chips, it uses 4164 type, so this would not work.  Some 16k RAM cards are jumperless because they do their own refresh.  Those might work in a //e in another slot similar to a Saturn style 128k card (because the Saturn bank switching scheme is based on the 16k RAM card design but with more banks), however there would be limited software support for such a thing.  I think the Saturn software including its RAM test would probably fail because they are wtitten for 128k instead of only 16k.  I'm not sure if Locksmith 5.0 would recognize and use a 16k RAM card in slot 1-7 like it does a Saturn card because I've never tried it.

 But certainly the TL;dr version is no, it generally won't work in a //e and to really test it you will need a ][+ or an appropriate clone.

I bought one to test my 4116's and it worked great with my Arduino Uno.

https://www.ebay.com/itm/165968504669?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1eom41CINSESZi67GITcppw1&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=165968504669&targetid=1583904486842&device=c&mktype=pla&googleloc=9028911&poi=&campaignid=19894961968&mkgroupid=148855406073&rlsatarget=pla-1583904486842&abcId=9307911&merchantid=6296724&gclid=Cj0KCQiA3uGqBhDdARIsAFeJ5r0hL0NPbqCWZgdvGDWT8_2VFICX--KRE_ts8zPQ1TQIApL43q5PmVIaAtE-EALw_wcB

tony359 wrote:

I know it's not for the Apple //e - I just would like to test it for an Apple II+. And wondering if it could work - expanding 64KB to 80KB - or replacing 16KB of the main RAM.

Yes, that card is perfectly compatible with the //e.  It will work in any slot on any model that has expansion slots that support INHIBIT memory cards, so you could even stick it into an Apple IIGS or Laser 128.  (Other examples of INHIBIT memory cards: Apple Language System, Saturn 128KB, Legend 1MB S'Card, Abacus 128KB Know Drive, Nexo 1MB Super Expander Plus)

Yours is a clone of this strapless 16K created by Unitron.  Unitron was a Taiwan-based maker of Apple II clones and accessories.  Their devices are easily distinguished by their blue circuit boards, which usually incorporate the word "UNITRON" into the foil layer.

IMG_1240.JPG

Your card omits the variable resistor at V1, which was a common shortcut in copies of Unitron's design.

Unitron clone.png

But, as softwarejanitor points out, most software that supports INHIBIT memory only looks for it in slot 0.   To use this card in an Apple //e, you will need software that supports INHIBIT memory cards in other slots besides slot 0.

Some examples and their applicability to using a 16K card in Apple //e:

• Disk Muncher (disk duplication software) - up to 3 cards supported, not automatically detected.  To use this card with Disk Muncher, go to the duplication screen and press SPACE to enter setup, then enter the slot number the card is in.
• Locksmith 6 (disk duplication, memory tester) - up to 7 cards supported, automatically detected.  Locksmith's "Fast Disk Copy Routine" will use this card to store 4 more tracks per pass, which reduces disk swapping.  Locksmith's "RAM Card Utils" will detect this card and test it, but the memory test is not very reliable.
• Diversi Copy (disk duplication) - up to 7 cards, automatically detected.
• Appleworks (productivity software) - only one card supported, requires third-party patch.  On an Apple //e or Apple IIGS you can use Plus-Works to use this card for additional desktop work space.

Bonus feature: in an Apple //e, you can use it in slot 3.

Any INHIBIT memory card will work in slot 3 without compatibility problems, including Saturn 128KB or 1MB Legend S'Card.

Some illustrations...

Locksmith 6.0

capture377.png

Disk Muncher 1.12

capture381.png

Good catch! I didn’t realize this was an Unitron clone.

S.Elliott wrote:

Bonus feature: in an Apple //e, you can use it in slot 3.

...

I tried my 128k Saturn card clone in slot 3 of my PAL Apple IIe and although I can see it and test it in Locksmith, it seems to interfere with the memory card in the AUX slot. Apple II Desktop was able to go into double hi-res mode, but it gets stuck on the progress bar screen. Otherwise it would have been a perfect use for the almost useless slot 3 on the PAL Apple IIe:

Saturn.JPG

tony359 wrote:

Is it possible that this card is also a language card?

Yes. That's basically another name for a 16K RAM card.

tony359 wrote:

ahhh amazing! This is a great addendum then. So this card doesn't need to be linked to one of the RAM sockets at all?

 

And which ICs are carrying the integer ROM?

There is no ROM on this kind of card.  The original Apple "Language Card" had one ROM, the Autostart F8.  However almost all the 3rd party ones dropped that.  This card is one of those that doesn't even include a socket for it.  The way you get INTBASIC on this card is it is loaded into the RAM.  INTBASIC only takes up about 6K, 2K is the F8 monitor ROM and there is 2K that is often used for Programmer's AID #1 and 6K that is usually empty.

One thing I just noticed is that although the holes are there for it, this card doesn't have capacitor C7 installed.  Perhaps it isn't absolutely necessary, but the "real" Unitron card has that cap.

softwarejanitor wrote:

One thing I just noticed is that although the holes are there for it, this card doesn't have capacitor C7 installed.  Perhaps it isn't absolutely necessary, but the "real" Unitron card has that cap.

 

Capacitor C7 is a polarized capacitor across the power supply rails: it connects between +5 volts and +12 volts.

The green board also omits capacitor C15 which connects -5 volts to 0 volts.

Copycat boards often omitted capacitors across the power rails because they aren't strictly required to get the circuit running.  The worst offender I've seen was Nexo's APX card, a clone of the AP-64 EPROM programmer.  It omitted two tantalum capacitors in the 25-volt power supply, which draws its current from the +5 volt bus supply, which results in unnecessary stress by feeding noise back into the motherboard's power rails.  Why run a 25-volt DC-to-DC converter from +5 volts instead of +12 volts?  Strange, careless. 

IMG_0770.png

Strange way to cut corners given those capacitors were not that expensive even back in the day.

If it was your card would you add back the missing caps?

softwarejanitor wrote:

Strange way to cut corners given those capacitors were not that expensive even back in the day.

 

If it was your card would you add back the missing caps?

 

 

Good point, they had already cut costs by susbstituting aluminum electrolytics for the tantalum capacitors UNITRON had used.  Maybe they omitted those capacitors for some other reason.  Capacitor C7 strikes me as undesirable because it couples the +5v rail to the +12v rail, which is exactly the opposite of what you want a bypass capacitor to do.  If there's a 3-volt ripple in the 12-volt rail (eg: backlash from the disk motor), wouldn't C7 couple it into a 3-volt ripple on the 5-volt rail too?

In the case of the RAM card, I wouldn't be inclined to add the missing capacitors unless I had a clear purpose for doing so.  There are other knockoffs of this particular 16K card on eBay, and they all omit C7 and C15 too.

But as for the EPROM programmer, I did add capacitors at the empty locations because its DC-to-DC converter caused noticeable noises through the speaker -- that suggested that it was putting stress on other components.  The silkscreen implied unpolarized capacitors, so I just used the highest-value multilayer capacitors I had on hand.  That helped  (audibly!)  but I've found photos that suggest the original AP-64 used tantalums at that location so I plan to swap them out before I use that EPROM programmer again.

IMG_0771.JPG