Apple II system clocks
- This article is a sub-page of Apple II peripheral cards.
, also know as real-time clocks
, were commodities in the early days of computing. A clock/calendar did not become standard in the Apple II
line of computers until 1987 with the introduction of the Apple IIGS
. Although many productivity programs as well as the ProDOS
operating system implemented time/date functions, users would have to manually enter this information every time they turned the computer on. Power users often had their Apple II's peripheral slots
completely filled with expansion cards, so third party vendors came up with some unique solutions in order to mitigate this problem with products like the Serial Pro and No-Slot Clock.
No-Slot Clock – Dallas Semiconductor
The No-Slot Clock
, also known as the Dallas Smartwatch (DS1216)
, was a 28-pin chip
-like device that could be used directly in any Apple II
or Apple II compatible with a 28-pin ROM
. Dallas Semiconductor
produced the device as an easy implementation for a real-time clock
for a variety of applications. The clock was powered by an embedded rechargeable lithium battery
, electrically disconnected until power was first applied to retain freshness. The non-replaceable battery had a life expectancy of 10 years and was capable of powering the clock for several thousand hours between charges.
In an Apple II, the No-Slot Clock resided under a 28-pin ROM chip. A user had to remove the ROM, insert the No-Slot Clock, and then reinsert the ROM chip into the top of the No-Slot Clock. The No-Slot Clock was both ProDOS and Dos 3.3 compatible, however a software driver had to be patched into ProDOS or integrated into the applicable DOS 3.3 program. Once the driver was installed it emulated the Thunderclock. The No-Slot Clock was installed in the following locations on the motherboard in the following computers:
Serial Pro – Applied Engineering
The Serial Pro
was a multifunction serial interface and clock/calendar card from Applied Engineering
. By combining the functions of two cards into one, the Serial Pro freed up an extra slot for those with highly-populated machines. This card was unique in the sense that it did not use "Phantom Slots" to achieve this functionality. Previous multifunction cards required that a secondary function be "mapped" to a different slot in the computer's memory, rendering that slot unusable. The card was capable of a 12/24 hour clock format, was both ProDOS
and DOS 3.3
compatible, and had on-screen time and date setting built into its ROM, eliminating the need to run a program in order to set the time. The battery was a GE
DataSentry rechargeable Ni-cad
battery which had a lifespan rating of 20 years. The card retailed for $139 during the late 1980s.
For more on the Serial Pro's communication capabilities, see its entry in Apple II serial cards.
Thunderclock Plus – Thunderware Incorporated
When the Thunderware Thunderclock Plus
was released in 1980, it quickly became the de facto standard for an Apple II system clock. When Apple Computer
released its new ProDOS operating system in 1984, a Thunderclock software driver came built-in. From that point on, all new Apple II system clocks strived to emulate the Thunderclock. The card itself was more compact than the earlier "The Clock" from Mountain Computers and contained two battery holders for off the shelf alkaline batteries
which were easily replaceable.
Time Master H.O. – Applied Engineering
The Time Master H.O. clock card from Applied Engineering
was possibly the most advanced system clock ever designed for any Apple II. The card utilized an onboard Z80 CPU
and was capable of emulating all other system clocks which preceded it. The Timemaster H.O. was powered by a GE
Datasentry rechargeable Ni-cad
battery which had a lifespan rating of 20 years. It was capable of 24 hour military format or more commonly, 12 hour with AM/PM format, millisecond timekeeping with an accuracy of 0.00005%, and an onboard timer which could time down any interval up to 48 days. It also maintained an internal calendar, separate of the 7 year cycle which ProDOS
mapped. Coincidentally the Timemaster H.O. was 100% ProDOS and DOS 3.3
The "H.O." in Timemaster H.O. stood for "High Output". This referred to the 8-pin Digital I/O port on the card for advanced applications. Through this port, one could hook up Applied Engineering's BSR X-10 interface and "command console" to remotely control lights and electrical appliances. The BSR system could send signals over existing 120 volt wiring, eliminating the need for additional wires. The system could also be used for low voltage implementations. The Timemaster H.O. retailed for $99 during the late 1980s while the BSR option cost an additional $29. The command console cost $39.
Other System Clocks
- AppleClock – Mountain Computer
- AppleCat – Novation
- California Computer Systems Clock – California Computer Systems
- CPS Multifunction Card – Mountain Computer
- The Clock – Mountain Computer
- Timemaster II H.O. – Applied Engineering
- Hayes Stack Chronograph – Hayes Microcomputer Products
Apple II peripheral cards