The IBM 370/138 was announced on June 30, 1976 and withdrawn November 1, 1983.
Although we do not have a complete system we do have the front of the Operators Control Panel as can be seen from the photographs and the picture of the installation is courtesy of IBM Corporate Archives.
The following are edited excerpts from an IBM Data Processing Division technical press release distributed on June 30, 1976.
The new IBM System/370 Model 138 combines a faster internal speed with a variety of features that can help the medium-scale user expand computer applications more easily and economically. The processor offers large main and reloadable control storage, performance increases under IBM virtual storage programming, and a number of standard features -- all at improved price/performance compared to the current System/370 Models 135 and 145.
The new model also offers increased system throughput -- the amount of time it takes to perform a given amount of work -- compared to the Models 135 and 145. For example, the batch processing throughput of a Model 138 running a representative set of selected DOS/VS jobs was measured at 1.18 to 1.38 times faster than a similarly configured Model 135. Additionally, the Model 138's internal speeds, or instruction execution rates, measured 29 to 36 percent faster than a Model 135. Because of differences in configurations and applications at customer sites, individual users may realize different performance results.
The new machine uses the same high-density monolithic Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) technology for main memory as other virtual storage System/370s. Each memory chip holds 2,048 bits of data. The Models 135 uses bipolar technology. The Model 138 is available with 524,288 or 1,048,576 characters of memory, double the maximum capacity of the Model 135.
The large memory capacity and improved performance of the new processor can ease application development for users wishing to expand their communications interactive and data base operations. The machine incorporates a reloadable control storage of 131,072 characters, five times the standard capacity of the Model 135 and four times the standard capacity of the Model 145. This portion of the processor stores programs that control the sequence of operations, as well as emulation and diagnostic routines.
The large control storage also accommodates standard and optional features available with the Models 138 and 148, allowing users to expand easily their system configurations. Most installed Models 135 and 145 can be upgraded to the new computer's internal performance levels at customer locations. The upgrades include extended control program support for OS/VS1 and VM/370. Machines that can be upgraded are Model 135s ranging from 262,144 to 524,288 characters of main memory, and Model 145-2s ranging from 262,144 to 2,097,152 characters of main memory.
The IBM System/370 Model 138 is available under a new Agreement for Lease or Rental of IBM Machines, which provides for either a 48-month contract period or a standard monthly rental. Monthly rentals will be approximately ten percent higher than monthly charges under the long-term lease.
Under a 48-month contract, the Model 138 can be leased for $8,730 a month with one-half million characters of main memory, and for $11,415 a month with one million characters. Monthly rental prices are $9,600 and $12,550. Purchase prices are $350,000 and $435,000.
First customer shipments of the Model 138 will be scheduled to begin as follows: Model 138 with one million characters of main memory, fourth quarter of 1976; and Model 138 with one-half million characters of memory, first quarter of 1977.
The Model 138 will be manufactured at IBM's System Products Division facility in Endicott, New York, where it was developed.
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